Quiz 260 – Previous Year’s Chemistry Questions with Explained Answers

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Which one of the following statements is NOT correct?

(a) All alkaline earth metals form hydrated salts

(b) Barium and strontium are found free in nature

(c) The presence of NaCI increases the rate of setting of plaster of Paris

(d) Gypsum is added to the cement to slow down its rate of setting

Explanation:

Barium and strontium are alkaline earth metals in group 2 of the periodic table. They do not occur in the free state. Barium occurs as barytesor heavy spar and as barium carbonate, also called witherite. Strontium is found in combined formas Celestine and stron hanite.

Ans- (b)


 

Assertion (A): Coal-based thermal power stations contribute to acid-rain.

Reason(R): Oxides of carbon are emitted when coal burns.

(a) Both A and R are true and R is the correct explanation of A.

(b) Both A and R are true but R is not the correct explanation of A.

(c) A is true, but R is false

(d) A is false, but R is true

Explanation:

Coal based thermal power plants contribute to acid rain because SO2 and NO2 are emitted from these plant, which formH2SO4 and HNO3 in atmosphere that cause acid rain. Oxides of carbon are emitted when coal burns but it does not contribute to acid rain.

Ans- (b)


 

Match List- I with List-II and select the correct answer using the codes given below the lists:

List – I

A. German silver

B. Solder

C. Bleaching powder

D. Hypo

List – II

  1. Tin
  2. Nickel
  3. Sodium
  4. Chlorine

Codes: A – B – C – D

(a) 1 – 2 – 4 – 3

(b) 2 – 1 – 3 – 4

(c) 2 – 1 – 4 – 3

(d) 1 – 2 – 3 – 4

Explanation:

Nickel is used in formation of German silver.

Tin is used in formation of Solder.

Bleaching powder contains chlorine while hypo contains sodium.

Ans- (c)


 

Assertion (A): In the periodic table of chemical elements, electron affinity is always found to increase from top to bottom in a group.

Reason (r): In a group, the atomic radii generally increase from top to bottom.

(a) Both A and R are true and R is the correct explanation of A.

(b) Both A and R are true but R is not the correct explanation of A.

(c) A is true, but R is false

(d) A is false, but R is true

Explanation:

In the periodic table of chemical elements, electron affinity generally decrease from to to bottom. In a group the atomic radii generally increase from top to bottom.

Ans- (d)


 

The offending substance in the liquor tragedies leading to blindness etc. is-

(a) ethyl alcohol

(b) amyl alcohol

(c) methyl alcohol

(d) benzyl alcohol

Explanation:

Methyl alcohol is the substance leading to blindness and physical ailment to the body.

Ans- (c)


 

Which one of the following polymers is widely used for making bullet proof material?

(a) Polyethylene

(b) Polycarbonates

(c) Polyamides

(d) Polyvinyl chloride

Explanation:

Polycarbonates are the polymer widely used in making bullet proof jacket and other equipment. Bulletproof jacket forms with different layers of substance, which provide resistance in penetrating from bullet.

Ans- (b)


 

Which one of the following is a mixed fertilizer?

(a) NPK

(b) Ammonium sulphate

(c) Urea

(d) CAN

Explanation:

NPK- contains nitrogen, phosphorus and potassium in different percentage. It is an ideal mixture of fertilizers.

Ans- (a)


 

Which one of the following has the highest fuel value?

(a) Charcoal

(b) Hydrogen

(c) Gasoline

(d) Natural gas

Explanation:

Hydrogen has the highest fuel value among the given options. Its fuelvalueis 150. Others fuel value charcoal, natural gas gasoline is 33, 35-50 and 50.

Ans- (b)


 

Which one of the following is NOT radioactive?

(a) Tritium

(b) Astatine

(c) Zirconium

(d) Francium

Explanation:

Zirconium is not a radioactive substance.

Ans- (c)


 

Which one of the following is the correct sequence in increasing order of molecular weights of the hydrocarbons?

(a) Butane, propane, ethane and methane

(b) Propane, butane, ethane and methane

(c) Methane, ethane, propane and butane

(d) Butane, ethane, propane and methane

Explanation:

The molecular weight can be measured by writing the formula of each hydrocarbon.

Ans- (c)

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