Sindh Mcat Nts 2017 — Solved Past Paper with Answers

Q1. Choose the lettered word or phrase that is most nearly opposite in meaning to the word in capital letters. MANDATORY:

• A. Dispassionate
• B. Obligatory
• C. Voluntary✓
• D. Confirmed

Explanation: Mandatory means something that is compulsory/obligatory to do. The opposite of which will be voluntary, which implies an element of intent in doing work.

Q2. Choose the lettered word or phrase that is most nearly opposite in meaning to the word in capital letters. HONESTY:

• A. Clever
• B. Dishonesty✓
• C. Resolution
• D. Failure

Explanation: Dishonesty is the word opposite in meaning to Honesty as it means to show deceitfulness in one's behavior.

Q3. Read the passage to answer question:Due to the extremely hot weather, the electric company is planning to turn off power in certain districts during the day. This will reduce the total demand for electricity and prevent a city-wide shutdown of electrical services. Power will not be out longer than two hours in your area. For further information, please visit our Web site at www.electricity.com. All areas affected by the shutdown are listed there, as well as the times that the power will be turned off in each area.Why is the power being turned off?

• A. To reduce total demand✓
• B. To save money
• C. To make it cooler
• D. To make the city pay its bill

Explanation: As it says in line 2 that “ to reduce the demand”. "Power is being shut down” so it will be safe to say that Option A is correct and makes sense even without the passage.

Q4. Read the passage and answer the following question:Due to the extremely hot weather, the electric company is planning to turn off power in certain districts during the day. This will reduce the total demand for electricity and prevent a city-wide shutdown of electrical services. Power will not be out longer than two hours in your area. For further information, please visit our Web site at www.electricity.com. All areas affected by the shutdown are listed there, as well as the times that the power will be turned off in each area.How long will power be off?

• A. Longer than two hours
• B. Less than two hours✓
• C. For one day
• D. Until the weather changes

Explanation: Line 4 of the passage clearly mentions that power will not be shut for more than two hours.

Q5. Complete the sentence by choosing the most appropriate option:There _ many students waiting to hear the results of the test.

• A. Has
• B. Have
• C. Was
• D. Are✓

Explanation: Students are plural. So, the helping verb should also be plural, which are “have” and “are”.Have can not be used here because it is used in perfect tense which has the 3rd form of verb while here we have the continuous form of verb i.e. “waiting”. So, the answer is D.

Q6. Complete the sentence by choosing the most appropriate option: Some people _ claim to be vegetarians actually allow themselves to eat fish and chicken.

• A. That
• B. Which
• C. Whom
• D. Who✓

Explanation: People are nouns referring to person, the best pronoun to use in this case thus will be to use “who”.

Q7. Identify errors in the sentences:During the day, there is often two guards at the entrance.

• A. During
• B. There is✓
• C. Guards
• D. No error

Explanation: It should be “there are” as guards are plural nouns so the helping verb used should also be plural.

Q8. Identify errors in the sentences:Because of their identical appearance and dress, the twins were often mistaken for each other.

• A. Because of
• B. Identical
• C. And dress
• D. Were
• E. No error✓

Explanation: There is no error in the sentence above according to grammar.

Q9. Choose the word most similar in meaning to the capitalized word: PROVOKE

• A. Deface
• B. Lionize
• C. Aggravate
• D. Aggravate✓

Explanation: To provoke something means to trigger something, the closest word to which will be "aggravate."

Q10. Choose the word most similar in meaning to the capitalized word:THREATENING:

• A. Flighty
• B. Aggressive✓
• C. Chaste
• D. Hallowed

Explanation: "Being threatening" means "to be very intimidating and horrifying". The closest word in meaning from above will be “aggressive”.

Q11. A student studied a drop of pond water with the low power of compound microscope and made the following exact drawing of an organism she observed, Which kingdom is the organism classified as?

• A. Protista✓
• B. Monera
• C. Metazoa
• D. Animalia
• E. Bryophyta

Explanation: Kingdom Protista has membrane-bound organelles, as shown in the diagram and a true nucleus. That is why option A is correct

Q12. The following organism moves by means of:

• A. Peristalsis
• B. Pinocytosis
• C. Porifera
• D. Protozoa
• E. Pseudopodia✓

Explanation: The organism moves by means of pseudopodia. That is why option E is the correct option. Pseudopodium is a temporary arm-like projection of a eukaryotic cell membrane that is developed in the direction of movement of the organism.

Q13. In a pyramid of energy, which level represents the greatest amount of energy?

• A. Producers✓
• B. First-order consumers
• C. Second-order consumers
• D. Third-order consumers
• E. Decomposers

Explanation: In all the ecological pyramids, producers (organisms that produce their own food) are found at the lowest trophic level. This trophic level contains the highest amount of energy. The energy in each trophic level of an energy pyramid is just 10 percent of the energy in the level below it.

Q14. The phenomenon known as crossing-over occurs during:

• A. Mitosis
• B. Meiosis✓
• C. Geographic distribution
• D. Active transport

Explanation: Crossing over is the exchange of genetic material between non-sister chromatids of homologous chromosomes during meiosis, which results in new allelic combinations in the daughter cells.

Q15. The following sequence of events occurs at the neuromuscular junction. Nerve impulse -> release of V -> end plate potential -> W produced in muscle fibre -> X release from sarcoplasmic reticulum -> Formation of Y -> muscle contraction. Which one of the following shows the correct sequence from V -> Y?

• A. Option A✓
• B. Option B
• C. Option C
• D. Option D
• E. Option E

Explanation: Neurotransmitters called acetylcholine (V) are released, and an action potential (W) is generated. After an action potential is generated in the muscle fibre, calcium ions (X) are released from the sarcoplasmic reticulum. Ca ions act on troponin and displace it so that myosin can attach to the sites on the actin molecule, forming an actomyosin (Y) complex for muscle contraction.

Q16. Which group of organisms has the following features? I. Three pairs of jointed legs II. Three-part segmented body III. One pair of antennae

• A. Arachnids
• B. Crustaceans
• C. Insects✓
• D. Myriapods

Explanation: Insects are arthropods that have three body segments, three pairs of legs, one pair of antennae, and many have one or two pairs of wings. The three body sections are called the head, the thorax, and the abdomen. Wings and legs are attached to the thorax, the middle section.

Q17. The table shows some characteristics of four different vertebrates. Which vertebrate is a reptile?

• A. A
• B. B✓
• C. C
• D. D

Explanation: Characteristics of Reptiles:✓ Reptiles are four-legged vertebrate animals.✓ Most reptiles lay eggs.The skin of reptiles is covered with scales. ✓ Reptiles have cold-blooded metabolisms. ✓ Reptiles breathe with the aid of lungs.

Q18. The diagram shows some organs of the digestive system. Where is amylase present?

• A. 1,4 and 5✓
• B. 1,2 and 3
• C. 2,6 and 4
• D. 3,5 and 4

Explanation: Amylase is mostly present in the mouth, in pancreatic juice, and ileum; hence, option A is correct. Amylase is not present in the liver, no enzyme is present in the large intestine and only pepsin (protease) is present in the stomach. That is why, all other options B, C and D are wrong.

Q19. Which bones meet at the elbow joint, and what kind of movement do they allow?

• A. Option A
• B. Option B
• C. Option C
• D. Option D✓

Explanation: At the elbow joint, the ulna and humerus meet, and they cause back-and-forth movement of the forearm. At the shoulder joint, the humerus and scapula meet, and there they cause full axial movement.

Q20. The diagram below represents the process of:

• A. Hydrolysis
• B. Condensation✓
• C. Neutralization
• D. Metabolism

Explanation: When two monomers join together to form a single product, with the removal of H2O, the process is called the condensation process. Hence, option B is correct.

Q21. Which of the following is correctly matched?

• A. AF, BG, CJ, DI, EH
• B. AH, BI, DF, CG, EJ✓
• C. AJ, BI, CH, DG, EF
• D. AH, BF, DG, CI, EJ

Explanation: To solve this quickly just match one or two organelles to their correct function,crossing out the wrong options while doing so. Peroxisomes carry out detoxification of alcohol which is only in option B so we can easily choose it,no other options have DF. To check others, we know that smooth ER deals with cholesterol and fats that is why E goes with J.Ribosomes carry out protein synthesis.Centrioles form astral rays.Lysosomes destroy foreign particles.Hence,AH, BI, DF, CG, EJ is correct.

Q22. Pyruvic acid is the end product of:

• A. Glycolysis✓
• B. Krebs cycle
• C. Oxidation
• D. Electron transport system

Explanation: Pyruvic acid is the end product of glycolysis, the first stage of cellular respiration. During glycolysis, one glucose molecule is enzymatically converted into two molecules of pyruvic acid in the cytoplasm, with a net gain of ATP and NADH. Glycolysis does not involve oxygen and precedes the Krebs cycle and electron transport chain, which occur in the mitochondria. The Krebs cycle processes acetyl-CoA, not pyruvic acid, and the electron transport system produces ATP and water. Oxidation is a broader term referring to electron loss and is not specific to producing pyruvic acid.

Q23. Humoral immunity is carried by a special group of cells called:

• A. B-cells✓
• B. Killer cells
• C. Helper cells
• D. Null cells

Explanation: Humoral immunity is also called antibody-mediated immunity. B-cells differentiate into plasma B cells that can produce antibodies against a specific antigen.

Q24. Identify the correctly matched pair relating to a term and its meaning/function/example:

• A. nitrogen cycle... Rhizopus
• B. denitrifying bacteria..change protein to ammonia
• C. biosphere.. where life exists✓
• D. lithosphere...water , air and soil on the surface of earth

Explanation: The biosphere is a global ecosystem composed of living organisms (biota) and the abiotic (nonliving) factors from which they derive energy and nutrients. Hence option C is correct. Rhizopus is a fungus that has nothing to with the nitrogen cycle. Denitrifying bacteria carry out the conversion of nitrates in the soil to free atmospheric nitrogen, not protein to ammonia. The lithosphere includes the brittle upper portion of the mantle and the crust, the outermost layers of Earth's structure, not water, air and soil.

Q25. Which of the following RNA sequences would be transcribed from the DNA sequence ATGGCTAGGAC?

• A. TACGGATCCTG
• B. UAGCGAUCCUG
• C. AUGCCUAGGAC
• D. UACCGAUCCUG✓

Explanation: DNA strand serves as the template for RNA synthesis. The RNA nucleotide sequence is complementary to that of DNA template strand except the presence of uracil in place of thymine. As we know that adenine base pairs with thymine and guanine with cytosine; the RNA sequence of given DNA strand would be UACGGAUCCUG. This makes option D correct answer.

Q26. Human cells maintain concentration gradients across their plasma membranes, such that there is a high sodium concentration outside the cell and a high potassium concentration inside the cell. Suppose that within the cell membrane are sodium leak channels or carrier proteins. These channels would allow sodium to:

• A. Move out of the cell by simple diffusion
• B. Move into the cell by simple diffusion
• C. Move out of the cell by facilitated diffusion
• D. Move into the cell by facilitated diffusion✓

Explanation: As the question mentions, there is a high concentration of sodium ions outside the cell, which means that through sodium leaky channels, the sodium ions should move inside the cell, not outside. The type of movement that occurs through channels or carrier proteins down the concentration gradient is called facilitated diffusion. That is why the answer is D.

Q27. The hormone labeled X in the diagram is often used in over-the-counter diagnostic tests to determine when ovulation has occurred. This hormone is:

• A. Estrogen
• B. Progesterone
• C. FSH
• D. LH✓

Explanation: The correct answer is LH, as it is the hormone whose surge triggers ovulation and is detected by ovulation prediction kits. Estrogen and progesterone play roles in preparing and maintaining the uterine lining, not in the detection of ovulation. FSH is involved in follicle development but not directly in ovulation prediction. Testosterone is a predominantly male hormone and irrelevant to this context.

Q28. Based on the peak levels of hormone X, on what day of the cycle is ovulation most likely to occur?

• A. Day 21
• B. Day 14✓
• C. Day 12
• D. Day 25
• E. Day 28

Explanation: Peak of LH hormone occurs at 14th day. So, the ovulation occurs at 14th day.

Q29. The hormone labeled X in the diagram is:

• A. Estrogen
• B. Progesterone
• C. FSH
• D. LH✓
• E. Testosterone

Explanation: Hormone X is LH because at 14th day of menstrual cycle, LH has highest peak which causes ovulation and stimulate ovaries to produce progesterone.

Q30. Which of the following statement(s) is/are correct regarding a nucleus? I.Stores wastes and other SubstancesII.Contains genetic materialIII.Helps in cellular transport systemIV.Control centre of the cell

• A. I only
• B. I&II
• C. II & III
• D. II & IV✓
• E. III & IV

Explanation: Nucleus is the control centre of the cell and stores the genetic material of the cell,so we say that statements II and IV are correct, making option D correct. Nucleus does not store wastes and other substances plus it also does not help in cellular transport system, that eliminate option A,B,C and E.

Q31. Bacteria having a tuft of flagella at one end are called:

• A. Peritrichous
• B. Monotrichous
• C. Lophotrichous✓
• D. Amphitrichous

Explanation: There are four types of flagellar arrangements based on the number and placement of flagella on the cell. These are, 1. Monotrichous - A single flagellum extends from one end of the cell. 2. Amphitrichous - A single flagellum or multiple flagella extend from two ends of the cell. 3. Lophotrichous - Tuft of flagella extend from one end of the cell. 4. Peritrichous – Multiple flagella randomly distributed over the entire bacterial cell. Thus, the correct answer is 'Lophotrichous.' Option A, B and D are incorrect as their description does not match the requirement of the question i.e. bacteria having a tuft of flagella at one end of the cell.

Q32. Cystic fibrosis patients lack a gene that codes for a transmembrane carrier of:

• A. Cl- ions✓
• B. Na+ ions
• C. K+ ions
• D. Ca2+ ions

Explanation: This is the correct answer. Cystic fibrosis (CF) is a genetic disorder caused by mutations in the gene that codes for the cystic fibrosis transmembrane conductance regulator (CFTR) protein. This protein is responsible for regulating the flow of chloride (Cl-) ions across the cell membranes of various organs, including the lungs, pancreas, and intestines. In CF patients, mutations in the CFTR gene disrupt the normal functioning of the CFTR protein, leading to an imbalance of salt and water in these organs. This imbalance results in the thick, sticky mucus characteristic of CF, which can cause respiratory problems, digestive issues, and other complications

Q33. Which features do animal cells share with plant cells?

• A. Option A
• B. Option B
• C. Option C✓
• D. Option D

Explanation: Mitochondria, cytoplasm and nucleus are found in both plant and animal cells. However, chloroplast is the organelle found in plant cells but lacking in animal cells.

Q34. Platyhelminthes means:

• A. Flatworms✓
• B. Roundworms
• C. Segmented worms
• D. None of the above

Explanation: Flatworms are known as Platyhelminthes. Free-living flatworms are mostly predators, and live in water or in shaded, humid terrestrial environments, such as leaf litter.

Q35. All of the following are mammals except the:

• A. Porpoise
• B. Shark✓
• C. Whale
• D. Walrus
• E. Seal

Explanation: Shark is a cartilaginous fish belonging to the class Chondrichthyes. All other options are wrong as they are mammals

Q36. In the pedigree of a family shown above, brown eyes are indicated as white circles and blue eyes as dark circles. Javeria and Juhi are twins. From this chart, it can be determined that:

• A. Tahir and Mary are homozygous for brown eyes
• B. Jawaria and Juhi are identical twins
• C. Juhi is heterozygous for blue eyes
• D. Juhi is homozygous for blue eyes✓
• E. Jawaria and Saad are homozygous for brown eyes

Explanation: It is imperative for a recessive trait present in a homozygous state to show up in phenotype so answer D is correct.

Q37. Viruses resemble living things because they:

• A. Circulate
• B. Move
• C. Reproduce✓
• D. Are crystalline
• E. Are able to respond to stimuli in the environment

Explanation: Only thing that makes a group of scientists want the virus to be classified as a living thing is its ability to reproduce. All other options are incorrect as non-living things can also exhibit these characteristics

Q38. A part of the digestive system that is not in contact with food is the:

• A. Small intestine
• B. Stomach
• C. Liver✓
• D. Large intestine
• E. Oesophagus

Explanation: The liver aids in digestion by producing bile, a fluid that emulsifies fats in the small intestine, breaking them down into smaller, more manageable droplets for absorption. While the liver doesn't "digest" food directly, it creates the bile necessary for fat digestion, which is then stored in the gallbladder before being released into the small intestine when food is present. All others are those parts of the digestive tract that come in contact with the food.

Q39. All of the following protect the body against the entrance of germs except:

• A. Tears
• B. Mucous membranes
• C. Ciliated cells
• D. Red blood cells,✓

Explanation: Red blood cells are responsible for transporting O2 via hemoglobin stored in them from the lungs to the body's cells and tissues. Options A, B, and C are incorrect because they are physical barriers (part of the first line of defense) that protect our body from germs.

Q40. The diagram below illustrates:

• A. Hemophilia
• B. Phenylketonuria
• C. Sickle cell anemia
• D. Down’s Syndrome✓

Explanation: Trisomy 21 i.e. the presence of 3 chromosomes at the 21th pair is the characteristic of Down's syndrome.

Q41. What will be the product of the following reaction?

• A. A
• B. B
• C. C
• D. D✓

Explanation: Step 1: Starting compoundWe have p-cresol (4-methylphenol).Step 2: Reaction with CHCl₃/NaOHThis is the Reimer–Tiemann reaction.In this reaction, an aldehyde group –CHO gets introduced at the ortho position to the –OH group.So product A is o-formyl-p-cresol (4-methyl-2-hydroxybenzaldehyde).Step 3: Reaction with HCNAn aldehyde reacts with HCN to give a cyanohydrin.The –CHO group becomes –CH(OH)CN.So compound B is o-(CH(OH)CN)-p-cresol.Step 4: Hydrolysis with H₃O⁺On hydrolysis, –CN group converts to –COOH.So the final product C is o-(CH(OH)COOH)-p-cresol.Step 5: Match with given optionsLooking at the options:(a) has –CH₂COOH (wrong, no hydroxyl group)(b) also has –CH₂COOH (wrong)(c) has –CH(OH)COOH but with two methyls (wrong position)(d) has –CH(OH)COOH correctly at the ortho position to OH, with a para –CH₃ substituent (correct).

Q42. The product for the given reaction is:

• A. Option A✓
• B. Option B
• C. Option C
• D. Option D

Explanation: Structure: Cyclohexene with a =CH₂ group (i.e., methylene cyclohexane).Explanation:This is the correct product.The –CH₂OH group loses water and forms a double bond at the exocyclic position.This is called an exocyclic alkene (double bond between ring carbon and exo carbon).Matches expected product of alcohol dehydration

Q43. What will be the product of the following reaction?

• A. A
• B. B
• C. C
• D. D✓

Explanation: Step 1: Starting compoundWe have p-cresol (4-methylphenol).Step 2: Reaction with CHCl₃/NaOHThis is the Reimer–Tiemann reaction.In this reaction, an aldehyde group –CHO gets introduced at the ortho position to the –OH group.So product A is o-formyl-p-cresol (4-methyl-2-hydroxybenzaldehyde).Step 3: Reaction with HCNAn aldehyde reacts with HCN to give a cyanohydrin.The –CHO group becomes –CH(OH)CN.So compound B is o-(CH(OH)CN)-p-cresol.Step 4: Hydrolysis with H₃O⁺On hydrolysis, –CN group converts to –COOH.So the final product C is o-(CH(OH)COOH)-p-cresol.Step 5: Match with given optionsLooking at the options:(a) has –CH₂COOH (wrong, no hydroxyl group)(b) also has –CH₂COOH (wrong)(c) has –CH(OH)COOH but with two methyls (wrong position)(d) has –CH(OH)COOH correctly at the ortho position to OH, with a para –CH₃ substituent (correct).

Q44. Which of the following values of heat of formation indicates that the product is least stable?

• A. - 94 kcal
• B. + 21.4 kcal
• C. - 231 kcal
• D. + 64.8 kcal✓

Explanation: In the context of heat of formation (ΔH), a negative value indicates that the formation of the compound is exothermic, meaning the compound is more stable compared to its constituent elements in their standard states.So, the least stable compound among the options provided would have the most positive (ΔH) value and option d has the most positive value ,hence that is the correct option.

Q45. The enthalpy of certain reactions at 273 K is -20.75 kJ. The enthalpy of the same reaction at 373 K (if heat capacities of reactants and products are the same) will be:

• A. －20.75 kJ✓
• B. -2075 kJ
• C. Zero
• D. －20.75 x 373/273 kJ

Explanation: As it is provided in the given statement that heat capacities of reactants and products are the same, therefore there will be no energy change in the reaction. By Kirchoff's Rule; ∆Cp=∆H2-H1/T2-T1∆Cp(T2-T1)=∆H2-H1As, ∆Cp= 0 , ∆H2=H1 , therefore;H2= -20.75KJ

Q46. Most abundant salt of sodium in nature is:

• A. NaNO3
• B. Na2SO4
• C. NaOH
• D. NaCl✓

Explanation: The most abundant salt of sodium in nature is sodium chloride (NaCl).The concentration of salt in seawater (its salinity) is about 35 parts per thousand; in other words, about 3.5% of the weight of seawater comes from the dissolved salts.

Q47. A gas that reacts with CaO and not with NaHCO3 is:

• A. None of these
• B. CI2✓
• C. O2
• D. N2
• E. Na

Explanation: Chlorine gas does react with calcium oxide (CaO) to form calcium chloride (CaCl2):Cl2 + CaO → CaCl2But it doesnot react with NaHCO3

Q48. Which of the following statements is correct?

• A. H3PO3 is dibasic and reducing✓
• B. H3PO3 is tribasic and reducing
• C. H3PO3 is tribasic and non-reducing
• D. H3PO3 is dibasic and non-reducing

Explanation: H3PO3 is correctly identified as dibasic because it has two -OH groups that can release hydrogen ions. Additionally, the presence of a P-H bond in its structure allows it to donate hydrogen atoms, making it a reducing agent. The incorrect options either misidentify it as tribasic or incorrectly label it as non-reducing.

Q49. Which of the following statements about H2S is false?

• A. It is a covalent compound
• B. It is a gas with bad smell
• C. It is a stronger reducing agent than H2O
• D. It is a weak base in water✓

Explanation: H2S acts as weak acid in water, not as a weak base. In H2S, the influence of the nucleus is less and hence, it can give away its electrons.

Q50. What is the volume in cm3 of 3.01 x 10^23 molecules of O2 gas at S.T.P.?

• A. 1000 cm3
• B. 11000 cm3
• C. 1120 cm3
• D. 11200 cm3✓

Explanation: 3.01*10^23 /6.02*10^23 = 0.5 mole at STP,1 mole of gas –––> 22,4 L 0,5 mole –––––––> x x= 11,2 L 11,2 L = 11200 cm3 As this is a numerical, it can only have one correct answer which is option D

Q51. The amount of solute present in the given amount of solvent is called:

• A. Molarity
• B. Molality
• C. Concentration✓
• D. Solubility

Explanation: The concentration of the solution tells you how much solute has been dissolved in the solvent. For example, if you add one teaspoon to two cups of water, the concentration could be reported as 1 teaspoon salt per 2 cups of water.

Q52. In the reaction 2Fe+Cl2 -> 2FeCl3

• A. Fe is reduced
• B. Fe is oxidized✓
• C. Cl2 oxidized
• D. None of the above

Explanation: The Oxidation state of iron(Fe) is changed from "0" to "+3". Hence it is oxidised.

Q53. The process in which electric current is used to carry out a non-spontaneous redox reaction is called:

• A. Electrolyte
• B. Electrolysis✓
• C. Metallic conductor
• D. None of the above

Explanation: Electrolysis is a process by which an electric current is passed through a substance to effect a chemical change. A chemical change is one in which the substance loses or gains an electron (oxidation or reduction).

Q54. The molecular structure of a hydrocarbon is shown below.

• A. Option A
• B. Option B✓
• C. Option C
• D. Option D

Explanation: B is a structural isomer of the structure shown above. Structure in A is the same as the structure shown. Structure C is not an isomer because it does not have the same number of carbon and hydrogen atoms as in the diagram shown. Structure D has a double bond that reduces two hydrogen atoms from it as compared to the structure shown that is why D can not also be an isomer of the diagram shown above.

Q55. The formula of Plaster of Paris is:

• A. (CaSO4).1/2H2O✓
• B. (CaSO4).5H2O
• C. (CaSO4).7H2O
• D. (CaSO4).9H2O

Explanation: The chemical name of the Plaster of Paris is calcium sulphate hemihydrate because half a molecule of water is attached with calcium sulphate. The chemical formula of plaster of Paris is CaSO4.1/2H2O

Q56. Ionic, covalent and co-ordinate covalent bonds are simultaneously present in the molecular geometry of:

• A. Ammonia
• B. Ammonium hydroxide✓
• C. Hydrochloric acid
• D. Water
• E. Methane

Explanation: There are 3 covalent , 1 coordinate covalent bond in NH4+ ion, and 1 covalent bond in OH−. There is an ionic bond between NH4+ and OH-.So, this species simultaneously has 3 different types of bonds.

Q57. All amino acids contain the functional group:

• A. NH2✓
• B. CO2
• C. S2-
• D. Both A and B

Explanation: All amino acids contain an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom and a part where radical attaches.-CO2 is different from -COOH. -CO2 can be present in esters.

Q58. Alanine, lysine and tryptophan are:

• A. Carbohydrates
• B. Lipids
• C. Enzymes
• D. Amino acids✓

Explanation: Alanine, lysine, and tryptophan are all building blocks of proteins. Each is a distinct amino acid with its own structure and properties. They are not carbohydrates, lipids, or enzymes.

Q59. What happens when one mole of ethane is mixed in the dark at room temperature with six moles of chlorine?

• A. There is no reaction.✓
• B. CH3CH2Cl and HCl are formed.
• C. CH3CCl3 and HCl are formed.
• D. CCl3CCl3 and HCl are formed.
• E. Carbon and HCl are formed.

Explanation: Hydrocarbons react with chlorine by free radical mechanism but this reaction only proceeds in the presence of light because it is necessary to break Cl-Cl bond. As in the given condition, it's a dark room, therefore there'll be no reaction in this case.

Q60. How would an ammino group affect the benzene ring for subsequent reactions?

• A. Deactivate the ring; meta directing
• B. Activate the ring; ortho-para directing✓
• C. Deactivate the ring; ortho-para directing
• D. Activate the ring; meta directing
• E. A and b

Explanation: Activate the ring: The ammino group is an electron-donating group due to its lone pair of electrons. This donation increases the electron density on the benzene ring, making it more reactive towards electrophilic aromatic substitution reactions. Thus, the presence of –NH₂ activates the benzene ring.Ortho-para directing: The –NH₂ group directs incoming electrophiles to the ortho and para positions relative to itself. This is because the lone pair on the nitrogen can participate in resonance with the benzene ring, stabilizing the positive charge that forms during the reaction at these positions. As a result, the ortho and para positions are favored for substitution over the meta position.

Q61. Which of the following would be the best solvent for an SN2 reaction?

• A. H2O
• B. CH3CH2OH
• C. CH3SOCH3✓
• D. CH3CH2CH2CH2CH2CH3

Explanation: Polar aprotic solvents are used in SN2 mechanism. As CH3SOCH3 is polar and also aprotic , so it is used as solvent in SN2 reactions.

Q62. A chemical reaction is catalyzed by a catalyst X. Hence, X:

• A. Increases activation energy of the reaction
• B. Does not affect equilibrium constant of the reaction✓
• C. Decreases rate constant of the reaction
• D. Reduces enthalpy of the reaction

Explanation: A catalyst provides an alternative reaction pathway with lower activation energy, increasing the reaction rate. It does not change the energies of reactants or products, so the equilibrium position remains unchanged. Therefore, the correct answer is B .

Q63. A compound was found to contain nitrogen and oxygen in the ratio 28g:80g. The formula of the compound is:

• A. NO
• B. N2O3
• C. N2O4
• D. N2O5✓

Explanation: Mass of nitrogen is 14 g and mass of oxygen is 16 g. Dividing nitrogen’s mass in compound (28g) by 14g gives us 2. Dividing oxygen’s mass in compound (80g) by 16g gives us 5. So we can now say that the molar ratio of N to O is 2:5 that means the formula is N2O5

Q64. When B- particles are sent through a thin metal foil, most of them go straight through the foil as:

• A. B- particles are much heavier than electrons
• B. B- particles are positively charged
• C. Most part of the atom is empty space✓
• D. B- particles move with high velocity

Explanation: They pass through tin metal foil because most space of the atom is empty, explained by Rutherford in his gold foil experiment.

Q65. Electronic configuration of M2+ ion is 2, 8, 14 and its atomic mass is 56 amu. The number of neutrons in its nucleus are:

• A. 30✓
• B. 32
• C. 42
• D. 52

Explanation: Total number of electrons in M2+ ions are 2+8+14=24, since they lost two electrons to become this ion that means neutral M will have 26 electrons. Since neutral atoms have the same numbers of electrons and protons so the number of protons in M is also 26. As the question states that the mass number of M2+ is 56. Mass number, being the sum of protons and neutrons, can be used to calculate neutrons, by subtracting protons from it(56-26=30)

Q66. The quantum numbers +½ and -½ for the electron spin represent:

• A. Rotation of the electron in clockwise and anticlockwise direction respectively
• B. Rotation of the electron in anticlockwise and clockwise direction respectively
• C. Magnetic movement of the electron pointing up and down respectively
• D. Two quantum mechanical spin states which have no classical analogue✓

Explanation: This is the most suitable option as it covers all aspects of describing the spin quantum number and its states.The two states +1/2 and -1/2, describes the spin of an electron. It is the term used for denoting the property of an electron only in Quantum physics and it does not have any proof in classical physics. That's why the term "no classical analogue" is used.

Q67. 1 liter of a gas weighs 2 g at 300 K and 1 atm pressure. If the pressure is made 0.75 atm, at which of the following temperatures will 1 L of the same gas weigh 1 g?

• A. 450 K✓
• B. 800 K
• C. 600 K
• D. 900 K

Explanation: So we know that,P₁V₁ / P₂V₂ = W₁T₁ / W₂T₂Substituting in the above formula we get,=> 1 × 1 / 0.75 × 1 = 2 × 300 / 1 × T₂=> 1 / 0.75 = 600 / T₂Cross Multiplying we get,=> T₂ × 1 = 600 × 0.75=> T₂ = 450 K

Q68. Which of the following pairs of gases have the same rate of diffusion?

• A. CO2 and N2O✓
• B. CO2 and CO
• C. NO2 and CO2
• D. CO2 and N2O4

Explanation: According to Graham's Law, the rate of diffusion or effusion is inversely proportional to the square root of molar mass. Both CO2 and N2O have the same mass (44). So, they have a similar rate of diffusion.

Q69. For the equilibrium reaction 2NO2 ⇌ N2O4 (g) (-61 kJ), increase of temperature would:

• A. Favour the Formation of N2O4
• B. Favour the Decomposition of N2O4✓
• C. No Effect on Equilibrium
• D. Stop the Reaction

Explanation: The reaction is exothermic (ΔH = -61 kJ) in the forward direction (2NO₂ → N₂O₄). Increasing temperature adds heat, which the system counteracts by shifting toward the endothermic reverse reaction. Thus, the equilibrium shifts to decompose N₂O₄ into NO₂.

Q70. The value K for H2(g) + CO2(g) <-> H2O(g) + CO(g) is 1.80 at 1000 C. If 1.0 mole of each H2 and CO2 are placed in 1 litre flask, the final equilibrium concentration of CO at 1000 C will be:

• A. 0.295 M
• B. 0.385 M
• C. 0.531 M
• D. 0.573 M✓

Explanation: The given reaction is :- H2(g)+CO2(g)⇌H2O(g)+CO(g) Initial moles : 1 1 0 0 At eqm : 1−x 1−x x x Now, KC=[H2O][CO]/[H2][CO2] 1.8=x.x/(1-x)(1-x) ⇒x2=1.8(1−x)2 Taking square root on both sides ⇒x=1.34(1−x)⇒2.34x=1.34 ⇒x=0.573 So, concentration of CO at eqb=0.573M

Q71. A row of 25 decorative lights, connected in series, is connected to a main transformer. When the supply is switched on, the lights do not work. The owner uses a voltmeter to test the circuit. When the voltmeter is connected across the third bulb in the row, a reading of zero is obtained. Which of the following cannot be the only fault in the circuit?

• A. The filament of one of the other bulbs has broken
• B. The filament of the third bulb has broken.✓
• C. The fuse in the mains transformer has blown.
• D. There is a break in the wire from the supply to the transformer.

Explanation: When a filament of a bulb in a series circuit is broken, it creates an open circuit causing the voltage to be maximum across that bulb. In this case, the third bulb's broken filament would result in a high voltage reading, not zero. The correct answer is that the filament of the third bulb has broken. This creates an open circuit, leading to the absence of current flow and hence zero voltage. The other options are incorrect because they do not explain the observed zero voltage across the third bulb.

Q72. Charges of +2 μC and -2 μC are situated at points P and Q respectively, as shown below. X is midway between P and Q. Which of the following correctly describes the electric field and the electric potential at point X?

• A. Option A✓
• B. Option B
• C. Option C
• D. Option D
• E. Option E

Explanation: As the electric field moves away from positive charges and towards negative charges, the direction of the electric field should be towards Q. Electric potential is a scalar quantity that means it should be added without considering the directions. At pSince the charges are equal and opposite with the same distance from point X, the potential at point X will be zero.

Q73. A fixed mass of gas in a thermally insulated container is compressed. After compression, the temperature of the gas will have:

• A. Fallen, since more molecules bombarded the container and so they must be moving slower
• B. Fallen, since more molecules collide more frequently with one another and so their average speed is lower
• C. Remains constant if the compression is very slow
• D. Risen, since doing work on the gas increases the kinetic energy of the molecules✓
• E. Risen, since there are more intermolecular collisions and so more heat is produced by them

Explanation: If an ideal gas is compressed adiabatically, its temperature rises because the heat produced cannot be lost to the surroundings. Each molecule has more KE than before because of collisions of molecules with moving parts of the wall (i.e., piston compressing the gas).

Q74. A fixed mass of an ideal gas absorbs 1000 J of heat and expands under a constant pressure of 20 kPa from a volume of 25 x 10-3 m3 to a volume of 50 x 10-3 m3. What is the change in the internal energy of the gas?

• A. －1000J
• B. －900J
• C. Zero
• D. ＋500 J✓
• E. ＋1000J

Explanation: This is the following solution:

Q75. In an experiment, an object was placed on the principal axis of a convex lens 25 centimeters away from the lens. A real image 4 times the size of the object was obtained. The focal length of the lens is:

• A. 20 cm✓
• B. 25 cm
• C. 33 cm
• D. 50 cm
• E. 100 cm

Explanation: The explanation is given below:u = 25 cmm = -4 [a real image so it must be inverted]v = - m * u = - * (-4) * 25 = 100 cmf = u * v / (u + v) = 25 * 100 / (25 + 100) = 2500 / 125 = 20 cmSo the focal length of the lens is 20 cm.

Q76. An object with constant mass rests on a horizontal surface whose coefficient of friction is 0.2. If a horizontal force F is applied to the object, what will be the effect(s) on the object? I. It may move with constant speed in the direction of F once it has been set in motion.II. It may remain at rest.III. It may accelerate.IV. It may move with constant speed in an opposite direction

• A. I, II and III only✓
• B. I and III only
• C. II and IV only
• D. IV only
• E. III only

Explanation: 1. It is possible that object starts to accelerate when the frictional force becomes greater enough due to objects motion to equalize the forward force, so the object starts moving at a constant speed.2. Now, if the force is less than product of coefficients of friction and weight of the object may remain at rest.3. If the force applied is greater than product of coefficient of friction and weight of the object, the object accelerates on the direction of force.

Q77. A person having a mass of 60 kilograms exerts a horizontal force of 200 Newtons in pushing a 90 kilogram object a distance of 6 meters along a horizontal floor. He does this at constant velocity in 3 seconds. The weight of this person approximately, in Newtons, is: (g=9.8m/s2)

• A. 40 N
• B. 90 N
• C. 200 N
• D. 400 N
• E. 600 N✓

Explanation: To find the weight of a person, use the formula W = mg, where W is the weight, m is the mass (60 kg), and g is the acceleration due to gravity (approximated here as 10 m/s2). Thus, the weight is calculated as:W = 60 kg × 10 m/s2 = 600 NTherefore, the correct answer is 600 N. Other options are incorrect as they underestimate the weight given the mass of 60 kg and the gravitational acceleration.

Q78. If 500 cm3 of gas, having a pressure of 760 millimeters of mercury, is compressed into a volume of 300 cm3 given the temperature remains constant, the pressure of the gas will be, in millimeters of mercury, approximately:

• A. 500 mm of Hg
• B. 900 mm of Hg
• C. 1,100 mm of Hg
• D. 1,270 mm of Hg✓
• E. 1,500

Explanation: Solution: This problem can be solved by ideal gas equation; PV=nRTSince, the temperature remains constant, therefore: Given: Initial Pressure of gas - 760mm of HgInitial Volume of gas - 560 cm³Final volume of gas - 300 cm³Find - Final pressure of gasSolution - The pressure of gas can be calculated by the help of formula; P1V1 = P2V2. In the equation, P1 and P2 are initial and final pressures and V1 and V2 are initial and final pressures.Keeping the values in equation-760x500 = P2x300P2 = 1266.67 mm of Hg.Hence, the pressure of gas is 1266.67 mm of Hg and the correct option closest to answer is D. 1,270.

Q79. Two springs fixed at one end are stretched by 5 cm and 10 cm, respectively, when masses 0.5 kg and 1 kg are suspended at their lower ends. When displaced slightly from their mean positions and released, they will oscillate with time periods in the ratio

• A. 1:√2✓
• B. 1:2
• C. 2:1
• D. √2:1

Explanation: This is the correct answer. The time period of a spring-mass system is given by T = 2π√(m/k), where T is the time period, m is the mass, and k is the spring constant. Since the spring constant is the same for both springs (as the same force produces the same extension), the ratio of the time periods will only depend on the ratio of the masses: T1/T2 = √(m1/m2). Substituting the given masses, we get T1/T2 = √(0.5 kg / 1 kg) = √(1/2) = 1/√2.

Q80. A unit of induction is said to exist at a point where the force per unit charge experienced by a positive test charge, moving with a velocity of 1ms-1 in the direction perpendicular to the field is 1 Newton. What is this phenomenon called?

• A. Gravitational Field
• B. Magnetic Field✓
• C. Magnetic Flux
• D. Flux

Explanation: The correct answer is Magnetic Field. A magnetic field is defined by the force it exerts on moving charges. In this question, the force per unit charge experienced by a test charge moving perpendicularly to the field indicates the presence of a magnetic field. The force is proportional to the velocity of the charge and the strength of the magnetic field.Option A (Gravitational Field) is incorrect because it deals with forces due to gravity, not magnetic forces.Option C (Magnetic Flux) is incorrect because it describes the number of magnetic field lines passing through a surface, not the force on a moving charge.Option D (Flux) is too general and does not specifically relate to magnetic fields affecting moving charges.

Q81. A _ is a positively charged particle with properties similar to the α-particle. Its mass is one fourth and charge is one half of that of an α-particle. It is smaller in size and carries less energy at the same velocity.

• A. Beta particle
• B. Gamma ray
• C. Neutron
• D. Proton✓

Explanation: The correct answer is a proton. A proton is a positively charged particle with a mass that is one fourth that of an alpha particle and a charge that is one half of an alpha particle, making it the particle described in the question.Beta particles are incorrect as they are negatively charged particles akin to electrons. Gamma rays are a form of electromagnetic radiation and do not have mass or charge. Neutrons have no charge, so they do not fit the description of a positively charged particle.

Q82. is defined as the sensation that sound produces in the ear of a listener and is clearly related to the frequency of sound. Frequency and _ are both measured in Hertz (Hz). Thus greater the frequency the greater the _ and lower the frequency lower the _.

• A. Quality ... Pitch ... Loudness ... Pitch
• B. Pitch ... Pitch ... Pitch ... Pitch✓
• C. Loudness ... Quality ... Pitch ... Quality
• D. Quality ... Quality ... Quality ... Quality
• E. Loudness ... Loudness ... Loudness ... Loudness

Explanation: The quality of a sound governed by the rate of vibrations producing it; the degree of highness or lowness of a tone is generally called pitch. Pitch is defined as the sensation of sound in the ear related to frequency.Pitches are measured by using a tool called hertz. Hertz measures one second of sound pitches and creates a calculated visual of the sound wave. Pitch is related to the frequency as pitch increases when the frequency is increased and decreases with the decrease in frequency.

Q83. Light can be polarized by: reflection double refraction scattering of light

• A. I only
• B. II only
• C. III only
• D. I and II only
• E. I, II and III✓

Explanation: 1. Scattering: When light interacts with particles or molecules in a medium, it can be scattered. Depending on the scattering mechanism, polarization can occur.2. Double refraction: Double refraction, also known as birefringence, is a property exhibited by certain transparent materials like calcite. In such materials, light is split into two beams, each polarized differently. This phenomenon is often used to polarize light.3. Reflection: When light reflects off a surface, the reflected light can be partially polarized, especially if the surface is non-metallic and the angle of incidence is specific (known as Brewster's angle). This polarized reflection is commonly used in polarizing filters.

Q84. Incident rays of light parallel to the principal axis of a convex lens, after refraction by the lens, will:

• A. Converge at the principal focus✓
• B. Converge inside the principal focus
• C. Converge outside the principal focus
• D. Converge at the center of curvature
• E. diverge as long as theý are close to the lens

Explanation: Incident rays of light parallel to the principal axis of the convex lens converge at the principal focus.A convex lens also known as a converging lens is thick in the middle and thin at the edges. It converges the light rays coming from a source on the principal focus. A principle focus of a convex lens is defined as the point on the principal axis on which the light rays coming parallel to the principal axis converge after getting refracted from the convex lens.

Q85. If two sounds have the same wavelength in air at the same temperature, what other property must they also have in common?Intensity Amplitude Frequency

• A. I only
• B. III only✓
• C. I and II only
• D. II and III only
• E. I, II and III

Explanation: If the two sounds have the same wavelength in air at the same temperature, it means they have the same speed of propagation in that medium. Since the speed of sound is constant, if the wavelength is the same, the frequency must also be the same. The relationship between frequency and wavelength is inversely proportionalv=f x wavelength

Q86. Which unit expresses work per unit charge?

• A. Hertz
• B. Watt
• C. Joule
• D. Volt✓
• E. Half-life

Explanation: The correct answer is Volt. A volt measures the electrical potential difference and is defined as the work done per unit charge, expressed as 1V = 1J/1C. This means that one volt is equivalent to one joule of work done per one coulomb of charge. The other options are incorrect because:Hertz measures frequency, not related to work or charge.Watt measures power, defined as work per unit time, not charge.Joule is a unit of energy or work, not per unit charge.Half-life is a concept related to radioactive decay, not applicable to work or charge.

Q87. The time of open vibration of a simple pendulum may be decreased by:

• A. Increasing the length of the pendulum
• B. Decreasing the length of the pendulum✓
• C. Using a heavier bob
• D. Using a lighter bob

Explanation: The 'time of one vibration' of the simple pendulum can be decreased by decreasing the pendulum length. The period of simple pendulum is given by;T=,2π√l/g,So there is direction relation between time period and length of pendulum. Therefore in order to decrease the time period the length of pendulum is decreased.Time period has nothing to concern with mass so option C & D are not related to the given question.

Q88. The sum of all forms of molecular energies in a thermodynamic system is known as:

• A. Entropy
• B. Enthalpy
• C. Internal energy✓
• D. Red shift

Explanation: Internal energy is the sum of potential energy of the system and the system's kinetic energy. It is the sum of all possible molecular energies in a thermodynamic system.

Q89. is also known as anti-electron.

• A. Photon
• B. Proton
• C. Positron✓
• D. Nucleon

Explanation: The positron, also known as the antielectron, is the correct answer because it is the antimatter counterpart of the electron, with +1 charge and annihilation upon collision with an electron. Photons have zero charge, protons have antiprotons as antiparticles, and nucleons are a collection of protons and neutrons, not the antiparticle of an electron.

Q90. When describing the isotopes of the same element, the most accurate statement is that they have:

• A. the same spin
• B. the same atomic mass but different atomic numbers
• C. the same atomic number but different atomic masses✓
• D. the same chemical properties and therefore can not be separated
• E. a coexistence limit, that is, no element can have more than three isotopes

Explanation: Those elements that have the same atomic number but a different mass number are referred to as isotopes.

Q91. In nuclear reactions, we have the conservation of:

• A. Mass Only
• B. Energy Only
• C. Momentum Only
• D. Mass-Energy and Momentum✓

Explanation: In a nuclear reaction, the total (relativistic) energy is conserved. It means that mass, energy and momentum all are conserved. The total momentum of the interacting particles before and after a reaction is the same

Q92. The lightest element which exhibits radioactivity is:

• A. Hydrogen
• B. Deuteron
• C. Tritium✓
• D. Helium

Explanation: Tritium is the only radioactive isotope of hydrogen and the other two have stable nuclei. As hydrogen is the lightest element in the periodic table, tritium will be the lightest radioactive isotope in the periodic table.

Q93. Nucleus with an excess of neutrons may decay radioactivity with the emission of:

• A. a neutron
• B. a proton
• C. an electron✓
• D. a positron

Explanation: When an unstable atomic nucleus has an excess of neutrons, it may undergo β− decay, where a neutron is converted into a proton and electron. This is why the correct answer is the emission of an electron. The other options, such as emitting a neutron, proton, or positron, do not align with the known decay processes of nuclei with excess neutrons.

Q94. Which pair includes a vector quantity and a scalar quantity respectively?

• A. Power, speed
• B. Work, potential energy
• C. Displacement, acceleration
• D. Force, kinetic energy✓

Explanation: Force is vector quantity and kinetic energy is scalar quantity.

Q95. A ball falls vertically and bounces on the ground. The following statements are about the forces acting while the ball is in contact with the ground. Which statement is correct?

• A. The force that the ball exerts on the ground is always equal to the weight of the ball.
• B. The force that the ball exerts on the ground is always equal in magnitude and opposite in direction to the force the ground exerts on the ball.✓
• C. The force that the ball exerts on the ground is always greater than the weight of the ball.
• D. Both A and C

Explanation: According to Newton’s Third Law of Motion, when a ball falls and bounces on the ground, the force that the ball exerts on the ground is always equal in magnitude and opposite in direction to the force the ground exerts on the ball. This is why Option B is correct. Option A is incorrect because the forces involved are not constant and equal to the weight of the ball. Option C is incorrect as it erroneously claims that the force is always greater than the weight of the ball, which is not necessarily true. Option D is incorrect because it includes both incorrect statements from Options A and C.

Q96. A car is traveling with uniform acceleration along a straight road. The road has marker posts every 100 m. When the car passes one post, it has a speed of 10 m/s and when it passes the next one, its speed is 20 m/s. What is the car's acceleration?

• A. 0.67 m/s2
• B. 1.5 m/s2✓
• C. 2.5 m/s2
• D. 6.0 m/s2

Explanation: A car is travelling with uniform acceleration along a straight road. The road has marker posts every 100 m, d = 100 mInitial speed of the car, u = 10 m/sFinal speed of the car, v = 20 m/sLet a is the acceleration of the car. It is equal to the rate of change of velocity per unit time.

Q97. A sample of an ideal gas may: expand adiabatically or expand isothermally. The net flow of heat into the gas from the exterior is:

• A. Positive in each case
• B. Negative for I and positive for II
• C. Positive for I and negative for II
• D. Zero in each case
• E. Zero in I and positive for II✓

Explanation: An adiabatic process is a thermodynamic process that involves the transfer of energy without transfer of heat or mass to the surrounding that it is zero in the case of I. While isothermal processes are those in which the temperature change is zero, that only implies the temperature change is zero, not the heat energy change.

Q98. With the usual notation, the first law of thermodynamics applied to one mole of an ideal gas can be written in the following form:CVΔT=ΔQ - PΔVIn a change for which Boyle's law is obeyed, which of the following would necessarily be zero?

• A. ΔQ
• B. CV
• C. ΔT✓
• D. P
• E. ΔV

Explanation: Boyle's Law states that when the temperature of a given mass of confined gas is constant, the product of its pressure and volume is also constant. So for Boyles law to be observed change in temperature (∆T) must be equal to zero.

Q99. Four particles independently move at the same speed in a direction perpendicular to the same magnetic field. Which particle is deflected the most?

• A. a copper ion
• B. a helium nucleus
• C. an electron✓
• D. a proton

Explanation: The deflection of a particle depends upon its mass to charge ratio. Since the mass of electron is too less as compared to its charge so it possesses maximum deflection. The electron would divert the most, the proton next and afterward the three particles. The amount they redirect relies upon their ionic states.

Q100. The circuit diagram shows a network of resistors each of resistance R. What is the effective resistance between the points X and Y?

• A. 2R/7
• B. R/2
• C. 5R/8✓
• D. 2R/3
• E. 3R/4

Explanation: Top two resistors placed in series have resistance, R+R=2R1 /R=1 /R+1 /2R=>1/R=3 /2R=> R=2/3*R (for combination two series with one parallel,on topmost side of diagram)1 /R=1 /R+1 /2R=>1/R=3 /2R=> R=2/3*R (for combination two series with one parallel,on topmost side ofdiagram)⅔ R+R=>(5/3)*R (for upper branch), which is in parallel with R of lower branch1 /R=3 /5R+R=>1/R=8 /5R=> R=5/8R,HENCE C is the correct option