Revision Series | Science and Tech | Chemistry | 118

September 13, 2023

Which one of the following is also known as 'wood spirit'?

(A) Methyl alcohol
(B) Ethylene glycol
(C) Ethyl alcohol
(D) Glycerol

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ANSWER: A

Consider the following pairs about acids and their common sources:
1. Apple: Malic acid
2. Tomato: Tartaric acid
3. Orange: Ascorbic acid
4. Tea: Formic acid
Which of the pairs given above are correct?

(A) 1 and 2 only
(B) 1 and 3 only
(C) 3 and 4 only
(D) 2 and 4 only

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ANSWER: D

Which of the following statement about physical property of carbon is not correct?

(A) Carbon is a non-metal found in various allotropic forms from soft powder to hard solid.
(B) All the allotropic forms of carbon are solids whereas its compounds exist in solid, liquid and gaseous state.
(C) Amorphous forms of carbon have low melting and boiling point compared to crystalline forms.
(D) Carbon is highly soluble in water and other common solvents.

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Answer: D

Physical properties of Carbon and its compounds

Carbon is a non-metal found in various allotropic forms from soft powder to hard solid.
All the allotropic forms of carbon are solids whereas its compounds exist in solid, liquid and gaseous state.
Amorphous forms of carbon and graphite are almost black in colour and opaque. Diamond is transparent and shiny.
Its amorphous forms have low melting and boiling point compared to crystalline forms.
Carbon is insoluble in water and other common solvents. But some of its compounds are soluble in water and other solvents. e.g., Ethanol, CO2 are soluble in water.

Consider the following statements about organic fertilizers:
1. Fertilizers containing only plant or animal based materials or those synthesized by microorganisms are called organic fertilizers.
2. Urea is example of an organic fertilizer.
Which of the statements given above is/are correct?

(A) 1 only
(B) 2 only
(C) Both 1 and 2
(D) Neither 1 nor 2

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ANSWER: A

Organic fertilizers

Fertilizers containing only plant or animal based materials or those synthesized by microorganisms are called organic fertilizers. These fertilizers can be prepared easily. This type of fertilizers is economical. (e.g) Vermi compost, compost.

Statement 1 is correct.

Inorganic fertilizers

The fertilizers prepared by using natural elements by making them undergo chemical changes in the factories are called inorganic fertilizers. (e.g) Urea, Ammonium sulphate and Super phosphate.

Statement 2 is not correct.

Which of the following is added to control the “setting of cement”?

(A) Gypsum
(B) Epsom
(C) Sand
(D) Clay

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Answer: A

Cement becomes hardened when it is mixed with water.
Gypsum plays a very important role in controlling the rate of hardening of the cement.
During the cement manufacturing process, a small amount of gypsum is added at the final grinding process.
Gypsum is added to control the “setting of cement”.

How does the matter change during liquefaction of gases?

(A) Gas to liquid
(B) Liquid to gas
(C) Solid to liquid
(D) Gas to solid

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ANSWER: A

“Liquefaction of gases” is the process by which substances in their gaseous state are converted to the liquid state. When pressure on a gas in increased, its molecules comes closer together, and its temperature is reduced, which removes enough energy to make it change from the gaseous to the liquid state. Option a is the correct answer.

Gases used in welding are :

(A) Oxygen and hydrogen
(B) Oxygen and nitrogen
(C) Oxygen and acetylene
(D) Hydrogen and acetylene

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ANSWER: C

One mole of hydrogen gas burns in excess of oxygen to give 290 KJ of heat. What is the amount of hear produced when 4g of Hydrogen gas is burnt under the same conditions

(A) 145 Ki
(B) 580 Kj
(C) 290 Kj
(D) 1160 Kj

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ANSWER: B

1 Mole of H2, (Hydrogen) =2 gm

Energy released by 4 gm = 290×2 = 580 Kj

Chemical name of washing soda is

(A) Sodium chloride
(B) Sodium hydrogen carbonate
(C) Sodium carbonate
(D) Sodium carbonate

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ANSWER: C

Washing soda is a chemical compound with the formula Na2CO3, known as sodium

carbonate, and it’s a salt of carbonic acid.

Which one of the following pairs is not correctly matched?
LIST -1 LIST-2
1. Fullerene - Organic compounds containing fluorine
2. Dry Ice - Solid carbon dioxide
3. Keratin - Protein found in the outer layer of human skin
4. Mustard gas - Poisonous liquid used is chemical warfare

(A) 1
(B) 2
(C) 3
(D) 4

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ANSWER: A

The metals that float when treated with water are -

(A) Copper and silver
(B) Iron and zinc
(C) Magnesium and calcium
(D) Aluminum and lead

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ANSWER: C

Magnesium and calcium are light metals and are less dense than water. When they are placed in water, they float because their density is less than the density of water. On the other hand, copper, silver, iron, zinc, aluminum, and lead are heavy metals and sink when placed in water because their density is greater than the density of water.

Which one of the following pairs is not correctly matched?
LIST -1 (Major Constituents) - LIST-2 (Fuel Gases)
A. Carbon monoxide, Hydrogen - 1. CNG
B. Butane, Propane - 2. LPG
C. Methane, Ethane -3. Coal gas
D. Hydrogen, Methane, Carbon Monoxide - 4. Water gas

(A) A — 2, B – 1, C – 3, D – 4
(B) A — 3, B – 2, C – 3, D – 1
(C) A — 4, B – 3, C – 1, D – 2
(D) A — 3, B – 2, C – 1, D – 4

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ANSWER: D

Fermentation of sugar leads to -

(A) Ethyl alcohol
(B) Methyl alcohol
(C) Acetic acid
(D) Chlorophyll

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ANSWER: A

Ethyl alcohol is formed by the fermentation of sugar, which is made of glucose and fructose.

Burning of hydrogen produces -

(A) Oxygen
(B) Ash
(C) Soil
(D) Water

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ANSWER: D

Hydrogen gas is highly flammable and burns in air at a very wide range of concentrations between 4% to 75% by volume.

Hydrogen gas cannot burn in absence of air. But by burning with oxygen it produces water.

Consider the following statements about Nylon:
1. Synthetic Fibre Nylon is the first fully processed synthetic fibre.
2. It was popular during the Second World War for the use of parachutes and rope materials for climbing.
3. Nylon thread is actually stronger than a steel wire.
Which of the statements given above is/are correct?

(A) 1 and 2 only
(B) 2 and 3 only
(C) 1 and 3 only
(D) 1, 2 and 3

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ANSWER: D

Synthetic Fibre Nylon is the first fully processed synthetic fibre. Statement 1 is correct

It was popular during the Second World War for the use of parachutes and rope materials for climbing. Statement 2 is correct
Nowadays, nylon has replaced natural silk in many textiles, and has become one of the most commonly used synthetic fibres.
Nylon fibre is strong, elastic and light.
It is lustrous and easy to wash, which has made it popular for the clothing industry.
We use many products made from nylon such as socks, ropes, tents, toothbrushes, car seatbelts, sleeping bags, curtains, etc.
Nylon thread is actually stronger than a steel wire. Statement 3 is correct