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Kpk Chemistry 2017 — Solved Past Paper with Answers
All 18 MCQs from Kpk Chemistry 2017, 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. Potassium dichromate acts as a strong...... agents?
- A. Dehydration
- B. Bleaching
- C. Reducing
- D. Oxidizing✓
Explanation: Potassium dichromate (K2Cr2O7) is a strong oxidizing agent because it readily gains electrons and is reduced to Cr3+ in acidic conditions. It oxidizes other substances by accepting electrons from them.
Why the other options are wrong
- A. Dehydration agents remove water from compounds. Potassium dichromate is not known for removing water; it doesn't typically act to dehydrate substances. Common dehydrating agents include H2SO4 and P2O5.
- B. Bleaching agents remove color from substances, often through oxidation. While potassium dichromate has oxidizing properties, it is not typically used for bleaching purposes. Common bleaching agents include chlorine and hydrogen peroxide.
- C. Reducing agents donate electrons and reduce other substances. Potassium dichromate cannot act as a reducing agent because it itself gets reduced during reactions, meaning it acts as an electron acceptor, not a donor. Common reducing agents include NaBH4 and LiAlH4.
Q2. All the acid derivative can be converted back into the corresponding acid by one common reaction?
- A. Ammonolysis
- B. Alcoholysis
- C. Hydrolysis✓
- D. Reduction
Explanation: All acid derivatives (like esters, amides, anhydrides, and acid chlorides) can be converted back into the corresponding carboxylic acid through hydrolysis. In hydrolysis, water (H2O) reacts with the acid derivative, breaking it down to yield the carboxylic acid.
Why the other options are wrong
- A. Ammonolysis involves the reaction of an acid derivative with ammonia NH3 to form an amide.
- B. Alcoholysis involves the reaction of an acid derivative with an alcohol to form an ester.
- D. Reduction involves the addition of hydrogen (or electrons) to an acid derivative to form alcohols or other reduced compounds.
Q3. Which one of the given is not a secondary pollutant?
- A. H2SO4
- B. CO2✓
- C. Ozone
- D. H2CO2
Explanation: Carbon dioxide is a primary pollutant because it is directly emitted from sources such as fossil fuel combustion and respiration. It does not form through reactions between other pollutants in the atmosphere.
Why the other options are wrong
- A. Sulfuric acid is a secondary pollutant. It forms in the atmosphere when sulfur dioxide (SO₂), a primary pollutant, reacts with water vapor.
- C. Ozone is a secondary pollutant. It forms in the atmosphere through photochemical reactions involving primary pollutants like nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the presence of sunlight.
- D. Carbonic acid forms when carbon dioxide (a primary pollutant) dissolves in water. Although it involves a primary pollutant, its formation through a reaction makes it a secondary pollutant.
Q4. When carbon undergoes sp2 hydridization then H-C-H bond angles are........?
- A. 120o✓
- B. 180o
- C. 109.5o
- D. 109o
Explanation: In sp² hybridization, the carbon atom forms three sigma bonds and has one unhybridized p orbital. The sp² hybrid orbitals are arranged in a trigonal planar geometry with bond angles of 120°.
Why the other options are wrong
- B. A bond angle of 180° is characteristic of sp hybridization, where the carbon atom forms two sp hybrid orbitals arranged linearly.
- C. A bond angle of 109.5° is characteristic of sp³ hybridization, where the carbon atom forms four sp³ hybrid orbitals arranged in a tetrahedral geometry.
- D. Similar to option C, 109° is close to the bond angle in sp³ hybridization, which is approximately 109.5°. It is not applicable to sp² hybridization.
Q5. Synthesis of DNA is also known as......?
- A. Transcription
- B. Translation
- C. Transmutation
- D. Replication✓
Explanation: DNA replication is the process of producing two identical replicas of DNA from one original DNA molecule. This process ensures that each daughter cell receives an exact copy of the DNA during cell division.
Why the other options are wrong
- A. Transcription is the process of synthesizing RNA from a DNA template. It involves the creation of messenger RNA (mRNA) based on the sequence of a DNA strand, which is then used for protein synthesis.
- B. Translation is the process by which the sequence of an mRNA molecule is used to build a protein. This process occurs in the ribosome, where tRNA molecules match amino acids to the corresponding codons on the mRNA strand.
- C. Transmutation generally refers to the conversion of one element or isotope into another, typically in the context of nuclear physics or alchemy. It is not related to the synthesis or replication of DNA.
Q6. Which one of the given is not are alkaine earth metal?
- A. Fr✓
- B. Sr
- C. Ba
- D. Mg
Explanation: Francium is not an alkaline earth metal. It belongs to Group 1 of the periodic table, known as the alkali metals. Francium is a highly reactive element, similar to other alkali metals like lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs).
Why the other options are wrong
- B. Strontium is an alkaline earth metal. It is in Group 2 of the periodic table and shares common properties with other alkaline earth metals, such as being reactive metals and forming divalent cations (Sr²⁺).
- C. Barium is also an alkaline earth metal. Like strontium, it is in Group 2 of the periodic table and exhibits similar chemical properties, such as forming Ba²⁺ ions and being highly reactive, especially with water.
- D. Magnesium is an alkaline earth metal as well. It is in Group 2 of the periodic table and is known for forming Mg²⁺ ions. Magnesium is essential for many biological processes and is used in various industrial applications.
Q7. Which one of the given is an ortholpara directing groups?
- A. NO2
- B. CN
- C. CHO
- D. OR✓
Explanation: The alkoxy group is an electron-donating group through resonance. It donates electron density to the benzene ring, stabilizing the ortho and para positions for incoming electrophiles, thus making it ortho/para-directing.
Why the other options are wrong
- A. The nitro group is a strong electron-withdrawing group. It is meta-directing, meaning it directs incoming electrophiles to the meta position relative to itself due to the electron-withdrawing effect, which destabilizes the ortho and para positions.
- B. The cyano group is also a strong electron-withdrawing group and is meta-directing for the same reasons as the nitro group. It withdraws electron density through both inductive and resonance effects, making the ortho and para positions less favorable for electrophilic attack.
- C. The formyl group is an electron-withdrawing group due to the presence of a double-bonded oxygen. It is also meta-directing, as it decreases electron density at the ortho and para positions, making them less favorable for incoming electrophiles.
Q8. Hydrolysis of an easter in the presence of NaCH is known as........?
- A. Saponification✓
- B. Esterfication
- C. Fermentation
- D. Decarboxylation
Explanation: Saponification is the process of hydrolyzing an ester with a strong base, such as sodium hydroxide (NaOH). This reaction produces a carboxylate salt (soap) and an alcohol. It is commonly used in the production of soap from fats and oils.
Why the other options are wrong
- B. Esterification is the process of forming an ester from a carboxylic acid and an alcohol, typically in the presence of an acid catalyst. This is the reverse of hydrolysis and does not involve the breakdown of an ester.
- C. Fermentation is a metabolic process that converts sugar to acids, gases, or alcohol. It is commonly associated with the production of ethanol and carbon dioxide from glucose by yeast. This process does not involve esters or their hydrolysis.
- D. Decarboxylation is the process of removing a carboxyl group from a molecule, releasing carbon dioxide (CO₂). This reaction is typical in organic chemistry but does not involve the hydrolysis of esters.
Q9. Which one of the given alkali metals form only normal oxide with oxygen?
- A. K
- B. Ro
- C. Li✓
- D. Na
Explanation: Lithium is the least reactive alkali metal and forms only a normal oxide (Li₂O) when it reacts with oxygen under normal conditions. It does not form peroxides or superoxides like the other alkali metals.
Why the other options are wrong
- A. Potassium reacts with oxygen to form potassium peroxide (K₂O₂) rather than a normal oxide. Potassium is more reactive than lithium and tends to form peroxides or superoxides.
- B. Rubidium reacts with oxygen to form rubidium peroxide (Rb₂O₂), not a normal oxide. Like potassium, rubidium is more reactive and tends to form peroxides or superoxides.
- D. Sodium reacts with oxygen to form sodium peroxide (Na₂O₂) rather than a normal oxide. Sodium is more reactive than lithium and tends to form peroxides or superoxides.
Q10. The overall structure of ethane is....
- A. Tetranedial✓
- B. Planar
- C. Pyramidal
- D. None of these
Explanation: Explanation will be added soon
Q11. Nitroles on catalytic hydrogenation produce......?
- A. Amines✓
- B. Amides
- C. Acetals
- D. Ammonia
Explanation: Catalytic hydrogenation of nitro compounds produces amines. The nitro group (–NO₂) is reduced to an amino group (–NH₂) in the presence of a catalyst, typically using hydrogen gas (H₂).
Why the other options are wrong
- B. Amides are not typically produced from the hydrogenation of nitro compounds. Amides have a carbonyl group (–C=O) bonded to a nitrogen atom, and their synthesis involves different reactions.
- C. Acetals are compounds with two -OR groups attached to a central carbon atom. They are not formed from the hydrogenation of nitro compounds.
- D. While ammonia (NH₃) can be produced by various processes, including catalytic hydrogenation of nitrogen, it is not the direct product of the hydrogenation of nitro compounds. The reduction of nitro compounds forms amines, not ammonia.
Q12. Protein presant in hemoglobin has the structure known as.....?
- A. Tertiary
- B. Quaternary✓
- C. Primary
- D. Secondary
Explanation: The quaternary structure of a protein refers to the arrangement of multiple protein subunits (individual polypeptide chains) in a multi-subunit complex. Hemoglobin is a quaternary protein consisting of four subunits: two alpha chains and two beta chains, each containing a heme group responsible for binding oxygen.
Why the other options are wrong
- A. The tertiary structure refers to the three-dimensional arrangement of the entire polypeptide chain of a protein, including all secondary structures (alpha helices, beta sheets) and any other loops or folds. Hemoglobin does have a tertiary structure, but the question specifically asks about the structure of the protein, which in the case of hemoglobin, involves multiple polypeptide chains.
- C. The primary structure of a protein is its linear sequence of amino acids. While this is an essential aspect of hemoglobin's structure, the question asks about the overall structure, which includes the arrangement of multiple subunits.
- D. The secondary structure of a protein refers to local folding patterns within a polypeptide chain, such as alpha helices and beta sheets. While hemoglobin's subunits have secondary structures, the overall structure of hemoglobin involves the arrangement of multiple subunits, making it a quaternary structure.
Q13. Wich one of given is not a traction of petroleum?
- A. Heavy oil
- B. Light naphtha
- C. Praffin
- D. None of these✓
Explanation: Option D is correct because all the other options (heavy oil, light naphtha, and paraffin) are indeed fractions of petroleum.
Why the other options are wrong
- A. Heavy oil is indeed a fraction of petroleum. It is one of the heavier fractions obtained during the refining process and typically includes substances like lubricating oils and heavy fuel oils.
- B. Light naphtha is also a fraction of petroleum. It is a lighter hydrocarbon mixture obtained during the refining process and is often used as a feedstock for producing high-octane gasoline and petrochemicals.
- C. Paraffin (also known as kerosene) is another fraction of petroleum. It is a medium-weight hydrocarbon mixture used as fuel for jet engines, heating, and lamps, and also as a solvent and in chemical manufacturing.
Q14. Ethers react with cold concentrated HCi to form........?
- A. Alkoxide ion
- B. Zwitterions
- C. Oxonium salts✓
- D. None of these
Explanation: When ethers react with cold concentrated HCl, they form oxonium salts. The oxygen atom in the ether molecule donates a pair of electrons to the hydrogen ion (H+) from the HCl, leading to the formation of an oxonium ion (R-OH2+). This reaction can be represented as: R-O-R' + HCl ---> R-OH2+ + Cl-Thus, the product is an oxonium salt, with the oxonium ion (R-OH2+) paired with a chloride ion (Cl-).
Why the other options are wrong
- A. Alkoxide ions (R-O-) are formed when alcohols lose a proton (H+) under basic conditions. Since the reaction in question involves an acid (HCl), the formation of an alkoxide ion is not possible. Therefore, this option is incorrect.
- B. Zwitterions are molecules that have both positive and negative charges, typically seen in amino acids where there are both acidic (carboxyl) and basic (amino) groups in the same molecule. Ethers reacting with HCl do not produce zwitterions. Therefore, this option is incorrect.
- D. This option is incorrect because, as explained above, the correct product of the reaction between an ether and cold concentrated HCl is an oxonium salt.
Q15. Amides can be reduced in presence of LiAH3 to.............
- A. Secondary amines
- B. Tertary amines
- C. Primary amines✓
- D. Quaternary amines salt
Explanation: Explanation will be added soon
Q16. Functional group of ketone is....
- A. -CO✓
- B. -CHO
- C. -COOH
- D. None of these
Explanation: Explanation will be added soon
Q17. Glycerol is type of alcohol having OH goup in petrochemical is........
- A. Two OH
- B. Three OH✓
- C. More than three OH
- D. None of these
Explanation: Explanation will be added soon
Q18. which one of the given is not a petrochemical
- A. Mineral Oil
- B. Naphihatane
- C. Table salt✓
- D. Wax
Explanation: Explanation will be added soon
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