Punjab Chemistry 2015 Paper 2 — Solved MCQs

Question 1

The elements placed at the extreme left of the periodic table are:

Accepted Answer

A. Metals — Another basis for classifying the elements in the periodic table is their metallic character. Generally, the elements on the left hand side, in the centre and at the bottom of the periodic table are metals, while the non-metals are in the upper right corner of the table.

Question 2

Chemical formula of milk of magnesia is:

Accepted Answer

C. Mg(OH)2 — A suspension of Mg(OH)2 in water is called milk of magnesia and it is used for treatment of acidity in stomach.

Question 3

The hydrolysis of borax can be prevented in presence of:

Accepted Answer

C. glycerine — The hydrolysis of borax is prevented in the presence of glycerine.

Question 4

The catalyst used in manufacturing H2SO, by contact process is:

Accepted Answer

A. V2O5 — SO2 obtained by burning sulphur or iron pyrites is oxidized to SO3 in the presence of V2O5 which acts as a catalyst.

Question 5

The anhydrous form of HCIO4 is:

Accepted Answer

D. Cl2O7 — CI2O7 is an anhydride of perchloric acid (HCIO4 ). It can be obtained at -10o C by dehydration of HCIO4 with P2O5.

Question 6

Which of following is non-typical transition metal:

Accepted Answer

C. Zn — Group IIB elements (Zn, Cd and Hg) do not have a partially filled d-subshell either as elements or in any of their ionic state. Neither do they show typical properties of transition elements to any appreciable extent (except complex formation). Similarly, IIIB (Sc, Y and La) is another group of elements which do not show many of the properties associated with typical transition elements.

Question 7

Which of the following is a heterocyclic compound?

Accepted Answer

C. Pyridine — The compounds in which the ring consists of atoms of more than one kind are called heterocyclic compounds or heterocycles. Naphthalene, Anthracene and Nitro-benzene are all aromatic compounds or their derivatives.

Question 8

Which type of reactions are given by alkanes?

Accepted Answer

D. Substitution — The alkanes or paraffins (Latin: parum = little, affins = affinity) under ordinary condition are inert towards acids, alkalis, oxidizing and reducing agents. However, under suitable conditions, alkanes do undergo two types of reactions. 1. Substitution Reactions 2. Thermal and Catalytic Reactions

Question 9

During nitration of benzene the active nitrating agent is

Accepted Answer

B. NO2+ — The introduction of NO2 group in benzene ring is called “Nitration”. The nitration of benzene takes place when it is heated with a 1:1 mixture of con. HNO3 and con.H2SO4 at 50- 55°C. Sulphuric acid reacts with nitric acid to generate nitronium ion, (NO2+ ).

Question 10

Ethyl chloride reacts with alcoholic KOH to give:

Accepted Answer

B. C2H5OH — In the presence of alcoholic KOH alkyl halides follow substitution reaction producing a substitution product. When ethyl chloride reacts with alc. KOH it produces ethyl alcohol.

Question 11

According to Lewis concept the ethers behave as

Accepted Answer

B. base — Ethers can act as Lewis bases by donating a pair of electrons from the lone pair on the oxygen atom to a Lewis acid. This interaction forms a coordinate covalent bond between the ether molecule and the Lewis acid.The oxygen atom in ethers has two lone pairs of electrons, making it capable of donating an electron pair. When a Lewis acid is present, such as a metal cation or a molecule with an electron-deficient center, the lone pair on the oxygen atom of the ether can interact with the Lewis acid.

Question 12

Cannizaro's reaction is:

Accepted Answer

D. Both A and B — Aldehydes that have no a -hydrogen atoms undergo Cannizzaro’s reaction. It is a disproportionation (self oxidation-reduction) reaction. Two molecules of the aldehyde are involved, one molecule being converted into the corresponding alcohol (the reduced product) and the other into the acid in the salt form (the oxidation product).

Question 13

Which of the following reagents will react with both aldehydes and ketones?

Accepted Answer

A. Grignard's reagent — Benedict's reagent, Tollen's reagent and Fehling's reagent are all used as identification tests for aldehydes so they do not react with ketones. Grignard reagent, on the other hand, reacts with both aldehydes and ketones and gives alcohols.

Question 14

Organic compounds having fruity smell are:

Accepted Answer

B. Esters — Esters have fruity smell and are used as artificial flavours.

Question 15

Which is not polymer:

Accepted Answer

A. Glucose — Glucose is a monosaccharide. Starch is a polymer of glucose.Protein is a polymer of amino acids.Nylon is a polymer of adipic acid and hexamethylene diamine.

Question 16

Urea contains Nitrogen.

Accepted Answer

B. 46% — Urea is a high quality nitrogeneous fertilizer. It contains about 46% nitrogen and is the most concentrated solid nitrogen fertilizer.

Question 17

Fungicides are the pesticides which: .

Accepted Answer

A. control the growth of fungus — The most important and widely used pesticides are insecticides (which kill insects), herbicides (which kill undesired plants) and fungicides (which control the growth of fungus on the plant).

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