Kpk Chemistry 2010 — Solved MCQs

Question 1

Which one is correct according to atomic size?

Accepted Answer

D. Cu>Co — Cu > Co is correct because copper (Cu) has a larger atomic size than cobalt (Co). This is because as you move down a group in the periodic table, atomic size generally increases due to the addition of new electron shells. Copper is located below cobalt in the same period, so it has more electron shells and a larger atomic size.

Question 2

Nelson's cell is used for the manufacturing of:

Accepted Answer

B. NaOH — NaOH is correct because the Nelson cell is used for the manufacturing of sodium hydroxide (NaOH) through the electrolysis of brine (sodium chloride solution). In the Nelson cell, brine is electrolyzed to produce chlorine gas (Cl2) at the anode and sodium hydroxide (NaOH) at the cathode.

Question 3

Gypsum has the molecular formula?

Accepted Answer

C. CaSO4.3H2O — CaSO4.3H2O is correct because gypsum has the molecular formula CaSO4·2H2O. Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. When gypsum is heated to a certain temperature, it loses water molecules and forms calcium sulfate hemihydrate, commonly known as plaster of Paris.

Question 4

Which of the following ions are responsible for the hardiness of water?

Accepted Answer

C. HCO-3 — This is correct because bicarbonate ions (HCO3-) are responsible for the hardness of water. Hard water contains dissolved calcium and magnesium ions, which can combine with bicarbonate ions to form calcium carbonate (CaCO3) and magnesium carbonate (MgCO3), which are insoluble and contribute to the hardness of water.

Question 5

Termite process is?

Accepted Answer

C. Reversible — The termite process is reversible in the sense that the products of wood digestion (such as simple sugars and other organic compounds) can be further metabolized or assimilated by the termite to support its growth and energy needs. In this sense, the process is reversible within the termite's digestive system.

Question 6

Molecule of oxygen is diatomic and behaves as:

Accepted Answer

A. paramagnetic — Explanation will be added soon

Question 7

Which one is the weakest acid?

Accepted Answer

C. HBr — This is the weakest acid among the given options. The H-Br bond is the weakest among the hydrogen halides, so HBr is the weakest acid among HF, HCl, HBr, and HI.

Question 8

The coordination number of iron in [Fe(CN)6]-4:

Accepted Answer

C. 6 — In the complex ion FeCN64-, iron is bonded to six cyanide ligands, resulting in a coordination number of 6.

Question 9

All the compounds are inorganic except:

Accepted Answer

D. (NH2)2CO — This is an organic compound. Urea is a compound found in urine and is also produced synthetically for use in fertilizers, plastics, and pharmaceuticals. It contains carbon-hydrogen bonds and is considered organic due to its carbon-based structure.

Question 10

Which of the following hydrocarbon will give product through the substitution reaction?

Accepted Answer

A. C2H4 — Ethylene can undergo substitution reactions, particularly under high-temperature conditions. For example, it can undergo halogenation to form products like dichloroethane (C2H4Cl2) in the presence of chlorine gas.

Question 11

All the C-C bond length in benzene is equal to?

Accepted Answer

D. 1.20 A — This is the correct answer. In benzene, all C-C bond lengths are equal and are approximately 1.40 Å due to the delocalization of π-electrons in the aromatic ring.

Question 12

The reaction is called:

Accepted Answer

B. Alkylation — Alkylation involves adding an alkyl group to a molecule. It is a common reaction in organic chemistry.

Question 13

Grignard Reagent reacts with ketones and produces:

Accepted Answer

C. Tertiary Alcohol — When a Grignard reagent reacts with a ketone, it adds to the carbonyl carbon, leading to the formation of a tertiary alcohol.

Question 14

Formaldehyde polymerizes to:

Accepted Answer

C. Paraldehyde — Paraldehyde is a cyclic trimer of formaldehyde, formed when formaldehyde undergoes polymerization. It is a liquid at room temperature and is used in some medical applications as a sedative and anticonvulsant.

Question 15

Taj Mahal, a monument in Agra is suffering from?

Accepted Answer

C. Land depression — The Taj Mahal is facing issues related to land subsidence or land depression. Due to excessive groundwater extraction in the region, the ground beneath the monument is gradually sinking. This subsidence can lead to structural instability and damage to the Taj Mahal over time.

Question 16

Sulphur dioxide is responsible for the formation of?

Accepted Answer

D. Acid rain — This is the correct answer. Sulfur dioxide reacts with water vapor and other chemicals in the atmosphere to form sulfuric acid (H2SO4), a major component of acid rain. Acid rain can have harmful effects on the environment, including damage to forests, aquatic ecosystems, and buildings.

Question 17

Metallic oxides are?

Accepted Answer

B. Basic — Metallic oxides are generally basic because they react with acids to form salts and water. They often show properties of bases, such as turning red litmus paper blue.

Question 18

Polystyrene is:

Accepted Answer

B. Polyvinyl benzene — Polystyrene is a synthetic aromatic polymer made from the monomer styrene. The correct chemical name for polystyrene is polyvinyl benzene, as it is a polymer of the vinyl group (-CH=CH2) attached to a benzene ring.

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