Punjab Chemistry 2022 Paper 1 — Solved MCQs

Question 1

Ethanol can be converted to ethanoic acid by:

Accepted Answer

C. Oxidation — Primary alcohols and aldehydes are readily oxidised to corresponding carboxylic acids by oxidising agents such as potassium dichromate in an acidic medium.

Question 2

Which of following will react with both aldehydes and ketones?

Accepted Answer

A. Grignard reagent — Benedicts reagent, Gehlings reagent and Tollens reagent are used in identification tests for aldehydes and they do not react with ketones. Grignard reagent reacts with both aldehydes and ketones. With aldehydes it gives primary and secondary alcohols and with ketones it gives tertiary alcohols.

Question 3

Which reagent reduces carboxylic acid to an alcohol?

Accepted Answer

D. LiAlH4 — Carboxylic acids on reaction with lithium aluminium hydride (LiAIH4) are reduced to alcohols.

Question 4

Which of these polymers is an addition polymer?

Accepted Answer

B. Polystrene — Polystyrene is an addition polymer and is obtained by the polymerization of styrene in the presence of a catalyst. Polystyrene is used in the manufacture of food containers, cosmetic bottles, toys and packing material, etc.

Question 5

Which is not a calcarious material?

Accepted Answer

B. Clay — The important raw materials used for the manufacture of cement are:1. Calcarious material (limestone, marble, chalks, marine shell) as source of CaO.2. Argillaceous material (clay, shale, slate, blast furnace slag) They provide acidic components such as aluminates and silicates,3. Other raw material being used is gypsum.

Question 6

Satrosphere region has range of:

Accepted Answer

D. 15-40 km — The stratosphere where the ozone layer exists in the atmosphere is approximately at 15 to 40 kilometer altitudes and is just above the troposphere which extends to an altitude of 0-15 kilometer from the earth.

Question 7

Residence time of NO in atmosphere is:

Accepted Answer

D. 4 days — The residence time of NO and NO2 in the atmosphere are 4 and 3 days respectively.

Question 8

Mark the correct statement:

Accepted Answer

A. Na+is smaller than Na — When a neutral atom loses one or more electrons, it becomes a positive ion. The size of the atom is decreased in this process because of two reasons. First, the removal of one or more electrons from a neutral atom usually results in the loss of the outermost shell. Second, the removal of electrons causes an imbalance in the proton-electron ratio. Due to the greater attraction of the nuclear charge, the remaining electrons of the ion are drawn closer to the nucleus. Thus, a positive ion is always smaller than the neutral atom from which it is derived. The radius of Na is 157 pm, and the radius of Na+ is 95 pm

Question 9

Which of the following sulphates is not soluble in water?

Accepted Answer

D. Barium sulphate — Barium sulphate is insoluble in water. It forms a white precipitate when it comes into contact with water, which settles at the bottom of the container. Due to its low solubility, barium sulphate is often used as a contrast agent in medical imaging procedures like barium swallow tests.

Question 10

Which element belongs to a group of IVA of periodic table?

Accepted Answer

C. Pb — The group IVA of the periodic table contains the following elements: C, Si, Ge, Sn, Pb

Question 11

The brown gas formed, when metal reduces HNO3 to:

Accepted Answer

C. NO2 — The brown gas formed when HNO_3 is reduced by metal to form nitrogen dioxide which is a poisonous brown gas with an irritating odou

Question 12

Which is the strongest acid?

Accepted Answer

D. HClO4 — The acid strength increases with the increase in the number of oxygen atoms. As the oxidation state of the halogen increases, the bonding electrons are shifted away from the Hatom and the tendency of the molecule to lose a proton increases. This accounts for the change of strength of oxyacids. The oxyacids of halogens show their strength in the order given below:HXO4>HXO3 >HXO2 >HXO

Question 13

Group VIB of transition metal contains:

Accepted Answer

C. Cr, Mo, W — Group VIB of transition elements contains: Cr, Mo, W

Question 14

Ether show the phenomenon:

Accepted Answer

C. Metamerism — This type of isomerism arises due to the unequal distribution of carbon atoms on either side of the functional group. Such compounds belong to the same homologous series. For example, diethyl ether and methyl n-propyl ether are metamers.

Question 15

Synthetic rubber is made by polymerization of:

Accepted Answer

D. Chloroprene — When acetylene is passed through an acidic solution of cuprous chloride and ammonium chloride and then allowed to stand for several hours at room temperature, vinyl acetylene and divinyl acetylene are obtained. If HCl is added to vinyl acetylene, chloroprene is obtained which readily polymerize to neoprene, used as synthetic rubber.

Question 16

Benzene can not undergo:

Accepted Answer

D. Elimination — The highly stable, delocalized electrons of benzene ring are not readily available for the nucleophillic attack like the electrons of alkenes. Therefore, the electrons of benzene ring do not assist in the attack of weak electrophiles. It means that more powerful electrophiles are required to penetrate and break the continuous sheath of electron cloud in benzene.Hence benzene undergoes electrophilic substitution. It is also oxidised in the presence of strong oxidising agent. It shows addition reaction in presence of appropriate catalyst.Benzene does not show any sort of elimination reaction.

Question 17

For which mechanisms, the first step involved is the same:

Accepted Answer

D. E1 and SN1 — :In E1 mechanism, like SN1 mechanism, the first step is the slow and ionization of substrate give carbocation

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