Quiz 284 – Previous Year’s Chemistry Questions with Explained Answers

Which one of the following statements is correct?

(a) Bordeaux mixture consists of sodium sulphate and lime.

(b) Zinc amalgams are used as a dental filling

(c) Liquid sodium is employed as a coolant in nuclear reactors

(d) Calcium carbonate is an ingredient of tooth paste.

Explanation:

Liquid sodium is employed as a coolant in nuclear reactor. Liquid sodium is an effective coolant which absorbs heat because of high specific heat.

Ans- (c)


 

Consider the following statements:

The purpose of adding sodium sulphate and sodium silicate to the detergent in a washing powder is-

  1. To keep the washing powder dry
  2. To maintain the alkalinity of the powder

Which of these statements is/are correct?

(a) Only 1

(b) Only 2

(c) Both 1 and 2

(d) Neither 1 nor 2

Explanation:

The purpose of adding sodium sulphate and sodium silicate to the detergent in washing powder is to keep the washing powder dry and to maintain the basically (Alkalinity) of the powder.

Ans- (c)


 

In an atom, the order of filling up of the orbitals is governed by-

(a) Hund’s rule

(b) Aufbau’s principle

(c) Pauli’s exclusion principle

(d) Heisenberg’s uncertainty principle

Explanation:

The order of filling up of the orbitals is governed by Aufbau’s principle, whichconveys that electrons are added to an atom one at a time, starting with lower energy orbital until all the electrons have been placed in an appropriate orbitals.

Ans- (b)


 

Match List – I with List – II and select the correct answers using the codes given below the lists:

List – I (Characteristic)

A. Zero Mass

B. Fractional charge

C. Fractional spin

D. Integral spin

List – II (Particle)

  1. Positron
  2. Neutrino
  3. Quark
  4. Photon

Codes: A – B – C – D

(a) 2 – 3 – 4 – 1

(b) 2 – 3 – 1 – 4

(c) 3 – 2 – 1 – 4

(d) 3 – 2 – 4 – 1

Explanation:

Zero Mass – Neutrino

Fractional charge – Quark

Fractional spin – Positron

Integral spin – Photon

Positron is antiparticles of electron. Neutrino is antiparticle of neutron. Quark has fractional charge.

Photons show integral spin.

Ans- (b)


 

Which one of the following elements is alloyed with iron to produce steel which can resist high temperatures and also have high hardness and abrasion resistance?

(a) Nickel

(b) Aluminium

(c) Tungsten

(d) Chromium

Explanation:

Chromium is generally mixed with iron to produce steel, which can resist high temperature and also have high hardness and abrasion resistance. Hardness of steel depends on the percentage of chromium.

Ans- (d)


 

Which of the following was used as a chemical weapon in the First World War?

(a) Mustard gas

(b) Hydrogen cyanide

(c) Water gas

(d) Carbon monoxide

Explanation:

Mustard gas was widely used as a chemical weapon in the First World War. Chemical weapons effect sense system of a person leading to asphyxiation and ultimately death.

Ans- (a)


 

Which one of the following is used as an anti-freeze for the automobile engines?

(a) Methanol

(b) Propyl alcohol

(c) Ethylene glycol

(d) Ethanol

Explanation:

Ethylene glycol is used as an anti-freeze agent for the automobile engine. In cold countries where temperature is below zero degree centigrade automobile engine cannot used efficiently due to freezing of fuel.

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

Ans- (c)


 

‘Yellow cake’, an item of smuggling across border is-

(a) a crude form of heroin

(b) uranium oxide

(c) a crude form of cocaine

(d) unrefined gold

Explanation:

Uranium oxide smuggled across border as yellow cake. Enriched uranium can be used in making illegal nuclear explosive that is dangerous to humanity.

Ans- (b)


 

The Chemical used as a ‘fixer’ in photography is-

(a) Ammonium persulphate

(b) Sodium sulphate

(c) Sodium thiosulphate

(d) borax

Explanation:

Sodium thiosulphate is used as a fixer in photography. It removes Ag fromnegative by formating complex with it.

Ans- (c)


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Quiz 220 – UPSC Previous Year’s Chemistry Questions

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