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Kpk Chemistry 2016 — Solved Past Paper with Answers
All 18 MCQs from Kpk Chemistry 2016, solved with the correct answer highlighted and a full explanation for every question. This is a free MDCAT KPK / ETEA past paper — no signup, no ads. Practise it interactively in timed mode, drill more with free MDCAT MCQs, or browse all KPK / ETEA papers.
Attempt this paper interactively →Q1. Which of the given metal sulphate is not soluble in water?
- A. BaSO4✓
- B. Na2SO4
- C. ZnSO4
- D. None of these
Explanation: Barium sulfate is well known for its very low solubility in water. It forms a white precipitate when mixed with water and is often used in medical imaging for this reason. Its insolubility is due to the strong ionic bond between Ba²⁺ and SO₄²⁻ ions that water molecules cannot easily disrupt.
Why the other options are wrong
- B. Sodium sulfate is highly soluble in water. Sodium (Na⁺) and sulfate (SO₄²⁻) ions readily dissolve and dissociate in water. Therefore, this option is incorrect as Na₂SO₄ is soluble in water.
- C. Zinc sulfate is also soluble in water. It dissolves to form Zn²⁺ and SO₄²⁻ ions in solution. Thus, this option is incorrect as ZnSO₄ is soluble in water.
- D. This option is incorrect because BaSO₄ is indeed not soluble in water, making option A the correct answer.
Q2. Which one of the given is not an alkali metal?
- A. Ra✓
- B. Rb
- C. Cs
- D. Fr
Explanation: Ra (Radium) is not an alkali metal. Radium is an alkaline earth metal, belonging to Group 2 of the periodic table. It is part of the same group as beryllium, magnesium, calcium, strontium, and barium. Alkaline earth metals are characterized by having two electrons in their outermost shell and are less reactive than alkali metals.
Why the other options are wrong
- B. Rb (Rubidium) is an alkali metal. It belongs to Group 1 of the periodic table, which includes lithium, sodium, potassium, rubidium, cesium, and francium. Alkali metals are highly reactive, especially with water, and have one electron in their outermost shell.
- C. Cs (Cesium) is an alkali metal. Like rubidium, cesium belongs to Group 1. It is highly reactive and is known for its low melting point and vigorous reaction with water.
- D. Fr (Francium) is an alkali metal. It is the heaviest and most unstable alkali metal, also belonging to Group 1. Francium is extremely rare and highly radioactive.
Q3. Transition elements usually exhibit ......valancies?
- A. Normal
- B. Variable✓
- C. Permanent
- D. Unchangeable
Explanation: Option B is correct. Transition elements often exhibit variable valencies, meaning they can have different valencies in different compounds.
Why the other options are wrong
- A. This option is incorrect because transition elements do not have a "normal" valency that remains constant in all compounds. Their valency can vary depending on the compound and the conditions.
- C. This option is incorrect because valencies of transition elements are not permanent. They can change based on the chemical environment.
- D. This option is incorrect because transition elements can have different valencies in different compounds, so their valencies are not unchangeable.
Q4. All the substances are organic except?
- A. Acetic acid
- B. Methane
- C. Urea
- D. Graphite✓
Explanation: Graphite is an inorganic substance. It is a form of carbon, but it is considered inorganic because it lacks the carbon-hydrogen bonds characteristic of organic compounds.
Why the other options are wrong
- A. This is an organic compound. Acetic acid, with the chemical formula CH3COOH, is a carboxylic acid and is considered organic because it contains carbon-hydrogen bonds.
- B. This is an organic compound. Methane, with the chemical formula CH4, is the simplest alkane and is considered organic because it consists entirely of carbon and hydrogen atoms bonded together.
- C. This is an organic compound. Urea, with the chemical formula CO(NH2)2, is an organic compound often used as a fertilizer. It contains carbon, hydrogen, nitrogen, and oxygen atoms.
Q5. The reactant which will react fast in the SN-2 reaction is?
- A. CH3F
- B. CH3CI
- C. CH3Br
- D. None of these✓
Explanation: Option D is the correct answer because CH3I (methyl iodide) is the most reactive among the given options in an SN-2 reaction. Iodine is the largest and most polarizable halogen, leading to the weakest and most easily broken carbon-iodine bond, thus favoring nucleophilic substitution.
Why the other options are wrong
- A. Fluorine is a small and highly electronegative atom, leading to a strong carbon-fluorine bond. This makes CH3F less reactive in an SN-2 reaction compared to the other options.
- B. Chlorine is larger than fluorine and less electronegative, so the carbon-chlorine bond is weaker than the carbon-fluorine bond. This makes CH3Cl more reactive than CH3F but still less reactive than the options with larger, more polarizable atoms.
- C. Bromine is larger and more polarizable than chlorine, making the carbon-bromine bond weaker and more susceptible to nucleophilic attack. Therefore, CH3Br is more reactive in an SN-2 reaction compared to CH3Cl and CH3F.
Q6. R-CH2-X is an example of ......halide.
- A. Isopropyl
- B. Secondary alkyl
- C. Primary alktl
- D. Both B and C✓
Explanation: Explanation will be added soon.
Q7. Clemmensen reducation of aldehydes yields....?
- A. Alkanes✓
- B. Alkenes
- C. Alcohol
- D. Ethers
Explanation: The Clemmensen reduction involves the conversion of aldehydes (or ketones) into alkanes by using zinc amalgam (Zn(Hg)) and hydrochloric acid (HCl) under heating.
Why the other options are wrong
- B. The Clemmensen reduction does not yield alkenes. Alkenes are not typically formed in this reaction.
- C. The Clemmensen reduction does not yield alcohols. It specifically converts aldehydes and ketones into alkanes.
- D. The Clemmensen reduction does not yield ethers. It is focused on the reduction of carbonyl compounds to alkanes.
Q8. The reaction between carboxylic acid and alcohol is called.....?
- A. Esterification✓
- B. Carboxylation
- C. Alcoholation
- D. Hydrolysis
Explanation: Esterification is the reaction between a carboxylic acid and an alcohol to form an ester and water. This reaction is catalyzed by an acid catalyst, such as sulfuric acid or hydrochloric acid.
Why the other options are wrong
- B. Carboxylation is the process of introducing a carboxylic acid group into a molecule, typically by reacting with carbon dioxide. It is not the reaction between a carboxylic acid and an alcohol.
- C. Alcoholation is not a standard term in chemistry. It is not typically used to describe the reaction between a carboxylic acid and an alcohol.
- D. Hydrolysis is the reaction of an ester with water to form a carboxylic acid and an alcohol. It is the reverse reaction of esterification.
Q9. Protein present in hemoglobin has the structure known as....?
- A. Primary
- B. Secondary
- C. Tertiary
- D. Quarternary✓
Explanation: The quaternary structure of a protein refers to the arrangement of multiple protein subunits (or polypeptide chains) to form a functional protein complex. Hemoglobin is a quaternary protein made up of four subunits, each containing a heme group that binds to oxygen.
Why the other options are wrong
- A. The primary structure of a protein refers to the linear sequence of amino acids in the polypeptide chain. It does not describe the overall structure of the protein.
- B. The secondary structure of a protein refers to the local folded structures that form within a polypeptide chain, such as alpha helices and beta sheets. It also does not describe the overall structure of the protein.
- C. The tertiary structure of a protein refers to the three-dimensional arrangement of all the atoms in the protein, including the interactions between secondary structural elements. While hemoglobin does have a tertiary structure, the question asks for the structure of the protein as a whole, which is quaternary for hemoglobin.
Q10. Mauve is an example of......dye?
- A. Direct
- B. Azo
- C. Acidic
- D. Basic✓
Explanation: Basic dyes are cationic dyes that are often used for dyeing acrylic fibers, paper, and leather. They are attracted to the negatively charged surface of the fibers. While Mauve is not a basic dye, based on the options provided, it is likely classified as an acidic dye due to its properties and chemical structure.
Why the other options are wrong
- A. Direct dyes are water-soluble dyes that are applied directly to the fabric from an aqueous solution. They are used mainly for dyeing cotton, wool, and silk. Mauve is not a direct dye.
- B. Azo dyes are synthetic dyes containing one or more azo groups (―N=N―) as the chromophore. These dyes are commonly used for coloring textiles, leather, and some foods. Mauve is not classified as an azo dye.
- C. Acid dyes are water-soluble dyes that are applied to fibers such as silk, wool, and nylon from an acidic dye bath. They are typically used in the dyeing of protein fibers. Mauve is not an acidic dye.
Q11. The marsh gas mainly consists of?
- A. So2
- B. H2S
- C. Ch4✓
- D. C2H4
Explanation: Marsh gas, or methane, is mainly composed of methane gas. It is produced by the anaerobic decomposition of organic matter in marshes and wetlands.
Why the other options are wrong
- A. SO2 (sulfur dioxide) is a different gas that is produced by the combustion of sulfur-containing compounds. It is not typically found in marsh gas.
- B. H2S (hydrogen sulfide) is a gas that has a characteristic rotten egg smell. While it can be produced in marshes through the decay of organic matter, it is not the main component of marsh gas.
- D. C2H4 (ethylene) is a different gas that is a hydrocarbon and is used in the production of plastics and as a plant hormone. It is not a major component of marsh gas.
Q12. The reaction used to locate the position of the double bond in alkene is....?
- A. Electrolysis
- B. Ozonolysis✓
- C. Polymerization
- D. Combustion
Explanation: Ozonolysis is a reaction that cleaves the carbon-carbon double bond in alkenes and produces carbonyl compounds. By analyzing the products of ozonolysis, the position of the double bond in the original alkene can be determined.
Why the other options are wrong
- A. Electrolysis is a process that uses an electric current to drive a non-spontaneous chemical reaction. It is not used to locate the position of a double bond in an alkene.
- C. Polymerization is a process in which monomers are combined to form a polymer. It is not used to locate the position of a double bond in an alkene.
- D. Combustion is a reaction in which a substance reacts with oxygen to produce heat, light, and usually carbon dioxide and water. It is not used to locate the position of a double bond in an alkene.
Q13. Grignard regents react with carbon dioxide (CO2) produce.....?
- A. Ketone✓
- B. Alcohol
- C. Polysaccharide
- D. Disaccharide
Explanation: Grignard reagents (RMgX) react with carbon dioxide (CO2) to form a carboxylate intermediate, which upon acidic workup, yields a ketone. This reaction is known as the Grignard reaction with carbon dioxide.
Why the other options are wrong
- B. Grignard reagents can react with carbonyl compounds (such as aldehydes and ketones) to form secondary and tertiary alcohols, but they do not react with carbon dioxide to produce alcohols.
- C. Polysaccharides are complex carbohydrates made up of multiple sugar units. They are not formed in the reaction of Grignard reagents with carbon dioxide.
- D. Disaccharides are carbohydrates composed of two monosaccharide units. They are not formed in the reaction of Grignard reagents with carbon dioxide.
Q14. Which one of the given is a non sugar?
- A. Monosaccharide
- B. Oligosaccharide✓
- C. Polysaccharide
- D. Disaccharide
Explanation: Oligosaccharides are carbohydrates composed of a small number (typically 3-10) of monosaccharide units joined together by glycosidic bonds. They are considered complex carbohydrates and are not classified as sugars.
Why the other options are wrong
- A. Monosaccharides are single sugar molecules, such as glucose and fructose. They are the simplest form of carbohydrates and are considered sugars.
- C. Polysaccharides are complex carbohydrates composed of many monosaccharide units joined together by glycosidic bonds. Examples include starch, glycogen, and cellulose. While they are not considered simple sugars, they are still classified as carbohydrates.
- D. Disaccharides are carbohydrates composed of two monosaccharide units joined together by a glycosidic bond. Examples include sucrose, lactose, and maltose. While they are not monosaccharides, they are still considered sugars.
Q15. Oxidation of primary alcohol in the presence of K2Cr2O7 produces?
- A. Carboxylic acid✓
- B. Ketone
- C. Alkyl halide
- D. Alkyne
Explanation: The oxidation of a primary alcohol in the presence of potassium dichromate (K2Cr2O7) typically produces a carboxylic acid. This occurs through the conversion of the alcohol to an aldehyde first, and then further oxidation to the carboxylic acid.
Why the other options are wrong
- B. The oxidation of a primary alcohol does not directly produce a ketone in the presence of K2Cr2O7. Ketones are typically formed from the oxidation of secondary alcohols.
- C. The oxidation of a primary alcohol with K2Cr2O7 does not produce an alkyl halide. Alkyl halides are usually produced through substitution reactions, not oxidation of alcohols.
- D. The oxidation of a primary alcohol with K2Cr2O7 does not produce an alkyne. Alkynes are typically synthesized through other methods, such as dehydrohalogenation of vicinal dihalides.
Q16. An example of condensation polymer is......?
- A. PVC
- B. Polythene
- C. Nylon✓
- D. Both A and B
Explanation: Nylon is a condensation polymer formed by the condensation reaction between diamines and diacids (or dibasic acids). The most common form of nylon, Nylon 6,6, is made from adipic acid and hexamethylenediamine.
Why the other options are wrong
- A. PVC is not a condensation polymer; it is a vinyl polymer formed by the polymerization of vinyl chloride.
- B. Polyethylene is also not a condensation polymer; it is a polymer of ethylene formed by addition polymerization.
- D. Neither PVC nor polythene are condensation polymers, so this option is not correct.
Q17. Photochemical smog is primarily caused by:
- A. O3
- B. NO2✓
- C. SO3
- D. CO2
Explanation: Photochemical smog appears to be initiated by nitrogen oxides that are emitted into the air as pollutants mainly from internal combustion engines. Absorbing the visible or ultraviolet energy of sunlight, it forms nitric oxide (NO) to free atoms of oxygen (O), which then combine with molecular oxygen (O2) to form ozone (O3). In the presence of hydrocarbons (other than methane), certain other organic compounds, and sunlight, various chemical reactions take place to form photochemical smog.
Why the other options are wrong
- A. As per the explanation, this is not the correct option.
- C. As per the explanation, this is not the correct option.
- D. As per the explanation, this is not the correct option.
Q18. The best source of iron is?
- A. Potato
- B. Tomato
- C. Milk
- D. Organ meat✓
Explanation: Organ meats, such as liver, are excellent sources of iron. They are also rich in other nutrients, including vitamin B12, which is important for red blood cell formation.
Why the other options are wrong
- A. Potatoes are not a particularly good source of iron. While they contain some iron, the amount is relatively low compared to other sources.
- B. Tomatoes are also not a significant source of iron. They are more known for their vitamin C content, which can help with the absorption of iron from other foods.
- C. While milk is a good source of calcium and other nutrients, it is not a significant source of iron.
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