Quiz 234 – UPSC Previous Year’s Chemistry Questions

Aluminum surface are often ‘anodized’. This means the deposition of a layer of –

(a) chromium oxide

(b) aluminum oxide

(c) nickel oxide

(d) zinc oxide

Explanation:

Nickel, chromium and aluminum metal have positive charge but zinc is less positive compared to these metals. Due to this less positive charge, aluminum rod attracts zinc from zinc solution and zinc deposits on aluminum rod.

Ans- (d)


 

A radioactive substance has a half-life of four months. Three-fourth of the substance would decay in-

(a) 3 months

(b) 4 months

(c) 8 months

(d) 12 months

Explanation:

After 4 months substance remains = ½

After 8 months substance remains = ¼

So, ¾ of substance would decay in 8 months.

Ans- (c)


 

Most of the explosions in mines occur due to the mixing of –

(a) hydrogen with oxygen

(b) oxygen with acetylene

(c) methane with air

(d) carbon dioxide with ethane

Explanation:

Oxygen reacts with acetylene and burns with explosion. Acetylene gas is used in lighting, vulcanization of rubber and acetic acid formation. It is also used in wedding to join iron layer.

Ans- (b)


 

Assertion (A): To dilute sulphuric acid, acid is added to water and not water to acid.

Reason (R): Specific heat of water is quite large.

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

(B) Both A and R is 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:

To dilute sulphuric acid, acid is added to water and not water to acid because specific heat of water is quite large and it can absorb large quantity of heat produced by sulphuric acid.

Ans- (a)


 

Assertion (A): Large cold storage plants use ammonia as refrigerant while domestic refrigerators use chlorofluorocarbons.

Reason (R): Ammonia can be liquefied at ambient temperature and low pressure.

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

(B) Both A and R is 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:

Large cold storage plants use ammonia as refrigerant while domestic refrigerators use chlorofluorocarbons because ammonia can be liquefied at ambient temperature and low pressure.

Ans- (a)


 

Assertion (A): A chemical reaction becomes faster at higher temperature.

Reason (R): At higher temperature, molecular motion becomes more rapid.

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

(B) Both A and R is 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:

Chemical reaction becomes faster at higher temperature because at high temperature, molecules have high kinetic energy and molecular motion is higher than normal temperature. Also due to high molecular motion chance of combining molecules is also high.

Ans- (a)


 

Match List I (Fuel gases) with List II (Major constituents) and select the correct answer using the codes given below the lists:

List – I (Fuel Gases)

A. CNG

B. Coal Gas

C. LPG

D. Water Gas

List – II (Major Constituents)

  1. Carbon monoxide, Hydrogen
  2. Butane, Propane
  3. Methane, Ethane
  4. Hydrogen, Methane, Carbon monoxide

Codes: A – B – C – D

(a) 2 – 1 – 3 – 4

(b) 3 – 4 – 2 – 1

(c) 2 – 4 – 3 – 1

(d) 3 – 1 – 2 – 4

Explanation:

CNG – Methane, Ethane

Coal Gas – Hydrogen, Methane, Carbon monoxide

LPG – Butane, Propane

Water Gas – Carbon monoxide, Hydrogen

Ans- (b)


 

Which one of the following is produced during the formation of photochemical smog?

(a) Hydrocarbons

(b) Nitrogen Oxide

(c) Ozone

(d) Methane

Explanation:

Photochemical smog is formed by Nitrogen Oxide.

Ans- (b)


 

An aqueous solution of copper sulphate is acidic in nature because the salt undergoes-

(a) dialysis

(b) electrolysis

(c) hydronlysis

(d) photolysis

Explanation:

An aqueous solution of copper sulphate is acidic in nature because the copper sulphate undergoes hydrolysis.

Ans- (c)


 

Consider the following statements:

  1. Drinking
  2. Washing clothes with soap
  3. Use in boilers
  4. Irrigating crops

Which of these statements are correct?

(a) 1 and 3

(b) 2 and 3

(c) 1, 2 and 4

(d) All of these

Explanation:

Hardness of water is due to chloride and sulphate of calcium and magnesium. Due to the presence of chloride and sulpahte of calcium and magnesium the clothes can be washed properly, also it cannot be used in boilers.

Ans- (b)

Related Articles:

Quiz 231 – UPSC Previous Years History Questions with Explained Answers

Quiz 209 – Geography Previous Year’s Questions

GS Quiz – Previous Year’s Question Paper

Quiz 193 – UPSC Previous Year’s Science Questions

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