Chemistry (Part-II) (UPSC)

Total Questions: 28

1. Which one among the following is called philosopher's wool? [2007]

(a) Zinc bromide
(b) Zinc nitrate
(c) Zinc oxide
(d) Zinc chloride

Correct Answer: (c) Zinc oxide

Solution:Philosopher's wool is a oxide of zinc a white powder used as a pigment, cosmetics, glass, inks and in zinc ointment.

2. Which one of the following does not contain silver? [2007]

(a) Horn silver
(b) German silver
(c) Ruby silver
(d) Lunar caustic

Correct Answer: (b) German silver

Solution:German silver has a color resembling silver, but is an alloy of primarily copper, nickel and zinc. Chlorargyrite is the mineral form of silver chloride (AgCl). It is also known as horn silver. Proustite is a sulfosalt mineral consisting of silver sulfarsenide, Ag, AsS,, known also as light red silver or ruby silver ore, and an important source of the metal. Silver nitrate is an inorganic compound with chemical formula AgNO,, It was once called lunar caustic because silver was called luna by the ancient alchemists.

3. What are Rubies and Sapphires chemically known as? [2008]

(a) Silicon dioxide
(b) Aluminium oxide
(c) Lead tetroxide
(d) Boron nitride

Correct Answer: (b) Aluminium oxide

Solution:Both Ruby and Sapphire are varieties of the mineral corundum, which is composed primarily of aluminium oxide (A1,0,). The difference in color between Ruby and Sapphire is due to trace impurities: The red color in rubies is primarily due to the presence of chromium (Cr³*) ions. Sapphires come in various colors (blue, yellow, green, pink, etc.) due to different trace elements. For example, the blue color in sapphires is typically caused by the presence of iron (Fe") and titanium (Ti) ions.

4. Which one of the following is also called Stranger Gas? [2008]

(a) Argon
(b) Neon
(c) Xenon
(d) Nitrous oxide

Correct Answer: (c) Xenon

Solution:Xenon is called the 'stranger' gas. This gas very un-reactive and heavier than air, that was why named strange (in greek it means 'xenon').

5. Which one of the following pairs of metals constitutes the lightest metal and the heaviest metal, respectively? [2008]

(a) Lithium and mercury
(b) Lithium and osmium
(c) Aluminium and osmium
(d) Aluminium and mercury

Correct Answer: (b) Lithium and osmium

Solution:The lightest metal in the periodic table is lithium (Li) with atomic number 3 density 0.53 kg/L. Lithium metal is extremely soft (and highly reactive) and so is unusable for many applications.

Osmium is a hard metallic element which has the greatest density of all known elements. It is twice as heavy as lead, and has a specific gravity of 22.59.

6. Lead, ingested or inhaled, is a health hazard. After the addition of lead to petrol has been banned, what still are the sources of lead poisoning? [2012-1]

1. Smelting units

2. Pens and pencils

3. Paints

4. Hair oils and cosmetics

(a) 1, 2 and 3 only
(b) 1 and 3 only
(c) 2 and 4 only
(d) 1, 2, 3 and 4

Correct Answer: (b) 1 and 3 only

Solution:People can become exposed to lead through occupational and environmental sources.

This mainly results from: inhalation of lead particles generated by burning materials containing lead, for example during smelting, recycling, stripping leaded paint and plastic cables containing lead and using leaded aviation fuel; and
ingestion of lead-contaminated dust, water (from leaded pipes) and food (from lead-glazed or lead-soldered containers) and from hand-to-mouth behaviour.

Children's innate curiosity and their age-appropriate hand-to-mouth behaviour result in their mouthing and swallowing lead-containing or lead-coated objects, such as contaminated soil or dust and flakes from decaying lead-containing paint.

7. Photochemical smog is a resultant of the reaction among : [2013-1]

(a) N*O_{2} O_{3} and peroxyacetyl nitrate in the presence of sunlight
(b) CO, O_{2} and peroxyacetyl nitrate in the presence of sunlight
(c) CO, CO_{2} and N*O_{2} at low temperature
(d) high concentration of N*O_{2} O_{3} and CO in the evening

Correct Answer: (a) N*O_{2} O_{3} and peroxyacetyl nitrate in the presence of sunlight

Solution:The burning of fossil fuel can create another atmospheric
pollution problem known as Photochemical Smog. Photochemical smog is a condition that develops when primary pollutants like oxides of nitrogen, Volatile organic compounds created from fossil fuel combustion interact under the influence of sunlight to produce secondary pollutants. The major chemical pollutants in Photochemical smog are NO and NO, VOCs(volatile organic compounds), Ozone(O) and PAN (Peroxyacetyl Nitrate). NO, decreases visibility due to yellowish colour. It also contributes to heart and lung problem. Ozone(O,) contributes to bronchial constriction, coughing and wheezing. PAN causes eye irritation, high toxicity to plants.

8. Whichofthe following is/aretheexample/examplesofchemical change? [2014-1]

1. Crystallization of sodium chloride?

2. Melting of ice

3. Souring of milk

Select the correct answer using the code given below.

(a) 1 and 2 only
(b) 3 only
(c) 1, 2 and 3
(d) None

Correct Answer: (b) 3 only

Solution:Chemical changes occur when a substance combines with another to form a new substance. Crystallization of sodium chloride is not a chemical as water of crystallization can be lost to get salt again. Similarly melting of ice is reversible. However souring of milk is a chemical change as it is not reversible and a new compound is formed.

9. Steel slag can be the material for which of the following? [2020-1]

1. Construction of base road

2. Improvement of agricultural soil

3. Production of cement

Select the correct answer using the code given below

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Correct Answer: (d) 1, 2 and 3

Solution:Steel slag, an unavoidable by-product in iron and steel production. Developed countries like Japan, USA have taken lead in making fertilisers using steel-making slag, says 2018's article in Financial Express So, #2 is correct. Steel Slag is used in road metal and bases, producing portland slag cement. It is also used for soil conditioning Says Handbook of Indian Bureau of mines page 6. So, All #3 statements correct.

10. Which one of the following polymers is widely used for making bullet proof material? [1995]

(a) Polyvinyl chloride
(b) Polyamides
(c) Polyethylene
(d) Polycarbonates

Correct Answer: (d) Polycarbonates

Solution:Polycarbonates are the polymer widely used in making bullet proof material. Bullet proof glass is made by layering a polycarbonate material between pieces of ordinary glass in a process called lamination.

A bullet fired will pierce the outside layer of the glass, but the layered polycarbonate glass material is able to absorb the bullet's energy and stop it.

Polycarbonate panels are used for covering advertising posters, construction of office buildings for sound proofing and polycarbonate is also used for making bullet proof jackets.

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