Chemistry (Part-XIV)

Total Questions: 50

1. Which of the following is present in nail polish remover? [S.S.C. Online CHSL (T-I) 21.01.2017 (Shift-II) ]

(a) Citric acid
(b) Acetone
(c) Ethylene
(d) Benzene

Correct Answer: (b) Acetone

Solution:Acetone (propanone, CH₃COCH₃) is a highly effective solvent widely used as the primary active ingredient in many nail polish removers. Its ability to quickly dissolve various organic compounds, including the polymers and resins found in nail polish, makes it ideal for this purpose. Other solvents like ethyl acetate or butyl acetate are also used, sometimes in acetone-free formulations.

2. Which of the following is added to commercial nitric acid for coloring? [S.S.C. Online C.P.O.S.I. (T-I) 2.07.2017 (Shift-I) ]

(a) Carbon dioxide
(b) Sulfur dioxide
(c) Colored adulteration
(d) Nitrogen dioxide

Correct Answer: (d) Nitrogen dioxide

Solution:Pure nitric acid (HNO₃) is colorless. However, commercial or concentrated nitric acid often appears yellowish or brownish due to the dissolution of nitrogen dioxide (NO₂) gas. This gas is formed when nitric acid decomposes slightly upon exposure to light or heat, or through the action of strong oxidizing agents. The presence of NO₂ gives it a distinctive color.

3. Which of the following statements are CORRECT? [S.S.C. Online CHSL (T-I) 15.03.2018 (Shift-II) ]

I. Esters are sweet smelling substances.

II. Esters are used in making perfumes.

III. Functional group of ester is 'R-O-R'.

(a) Only I and II
(b) Only I and III
(c) Only II and III
(d) All I, II and III

Correct Answer: (a) Only I and II

Solution:I. Esters are sweet smelling substances. This statement is CORRECT. Esters are known for their pleasant, fruity, and floral fragrances. They are responsible for the natural aromas of many fruits and flowers.

II. Esters are used in making perfumes. This statement is CORRECT. Due to their characteristic sweet and fruity smells, esters are widely used as artificial flavorings in food and beverages, and as fragrances in perfumes, cosmetics, and soaps.

III. Functional group of ester is 'R-O-R'. This statement is INCORRECT. The functional group of an ester is R-COO-R' (or RCOOR'). The functional group 'R-O-R'' represents an ether.

4. What is the formula of acetonitrile? [S.S.C. Online Constable GD 3.03.2019 (Shift-I) ]

(a) CH₂CHCN
(b) C₂N₂
(c) CH₃OCN
(d) CH₃CN

Correct Answer: (d) CH₃CN

Solution:Acetonitrile is an organic compound with the chemical formula CH₃CN. It is the simplest organic nitrile, often used as a polar aprotic solvent in organic synthesis and in the purification of butadiene. It's also known as methyl cyanide.

5. The chemical formula of aluminium nitride is- [S.S.C. Online CHSL (T-I) 31.01.2017 (Shift-II) ]

(a) AN
(b) AIN
(c) AlNi
(d) ANi

Correct Answer: (b) AIN

Solution:Aluminium nitride (AIN) is a covalent compound of nitrogen and aluminium, which does not occur naturally. It is made from the synthesis of aluminium and nitrogen. It is a material with high thermal conductivity and low electrical resistivity. It also has high hardness. Due to its above properties, this material has been considered very useful for future optics, electronics, and lighting.

6. Which of the following is a sweet smelling substance? [S.S.C. Online MTS (T-I) 8.08.2019 (Shift-I) ]

(a) Ethanol
(b) Ammonia
(c) Methanol
(d) Esters

Correct Answer: (d) Esters

Solution:Esters are a sweet-smelling substance. Generally, esters are formed by reacting with carboxylic acid and alcohol. Perfume is also made using esters.

7. The explosive of trinitrotoluene (TNT) is done by a mixture of which the following? [C.P.O. S.I. 5.06.2016 (Shift-II) ]

(a) Ammonium chloride
(b) Ammonium nitrite
(c) Ammonium sulfate
(d) Ammonium nitrate

Correct Answer: (d) Ammonium nitrate

Solution:Trinitrotoluene (TNT) is a powerful explosive on its own. However, for many commercial and military applications, it is often mixed with ammonium nitrate to create more powerful and cost-effective explosive compositions. Mixtures like Amatol (TNT + ammonium nitrate) are common. Ammonium nitrate acts as an oxidizer, increasing the explosive yield. The question phrasing "explosive of TNT is done by a mixture of which the following" is a bit awkward, but it refers to enhancing TNT's explosive power or forming composite explosives.

8. Which of the following is used for making gunpowder? [S.S.C. Online C.P.O.S.I. (T-I) 2.07.2017 (Shift-I) ]

(a) Methyl alcohol
(b) iron oxide
(c) nitro glycerol
(d) copper sulfate

Correct Answer: (c) nitro glycerol

Solution:Nitro glycerol is used to make gunpowder. Nitroglycerin is a colorless, heavy, oily, explosive substance. It is also called tri nitroglycerin (TNG) or glycerol tri nitrate or Nobel's oil. It is used to make explosives such as dynamite.

9. Nitrification is the biological process of converting- [S.S.C. Online Graduate Level (T-I) 2.09.2016 (Shift-I) ]

(a) N₂ into nitrate
(b) N₂ into nitrite
(c) Ammonia into nitrite
(d) Ammonia into N₂

Correct Answer: (c) Ammonia into nitrite

Solution:Nitrification is the process in which ammonia (NH₃) Oxidation takes place in the form of nitrite i.e. NO₂ these nitrites are later converted into nitrate.

10. A catalyst is a substance that _____ a chemical reaction. [S.S.C. Online Stenographer 13.09.2017 (Shift-I) ]

(a) first increases then decrease.
(b) increases
(c) decreases.
(d) brings no change.

Correct Answer: (b) increases

Solution:A catalyst is a substance that increases the rate of a chemical reaction. When the rate of a chemical reaction increases in the presence of a substance, it is called catalysis. The catalyst itself does not participate in the reaction but affects the rate of action.

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