Miscellaneous And Useful Chemical Compounds (Part-VI)

11. Which of the following is not a chemical change? [S.S.C. Online MTS (T-I) 11.10.2017 (Shift-I)]

(a) Conversion of carbohydrates to energy
(b) Converting water into steam
(c) Making curd from milk
(d) Heating coal

Correct Answer: (b) Converting water into steam

Solution:In a chemical change, some new substance must always be formed, i.e., one or more new substances can be formed by the chemical reaction on a substance, whereas in physical change only the physical state of the substance changes. The chemical form does not change. Hence, the conversion of water into steam is a physical change, as it is H₂O in both cases.

12. Electropositive atoms constitute [S.S.C. Online MTS (T-I) 11.10.2017 (Shift-I)]

(a) Negative ions
(b) Positive ions
(c) Covalent Contract
(d) Metallic contract

Correct Answer: (b) Positive ions

Solution:Electropositive atoms have the ability to easily convert electrons from their outer orbitals to positive ions. For example, sodium (Na) and potassium (K) respectively lose one electron each from their outer orbit and get converted into Na⁺ and K⁺ ions. Similarly, magnesium (Mg) and calcium can give up two electrons to form Mg²⁺ and Ca²⁺ ions.

13. Soil is an example of which of the following? [S.S.C. Online MTS (T-I) 16.09.2017 (Shift-III)]

(a) Homogeneous mixture
(b) Compound
(c) Molecule
(d) Heterogeneous mixture

Correct Answer: (d) Heterogeneous mixture

Solution:Many types of mutually miscible and immiscible substances are found in soil. So the soil is a heterogeneous mixture.

14. A mixture of cement, gravel, coarse sand, and water is called [S.S.C. Online MTS (T-I) 4.10.2017 (Shift-II)]

(a) mortar
(b) concrete
(c) slurry
(d) moderator

Correct Answer: (b) concrete

Solution:Concrete is prepared by mixing cement, pebbles, coarse sand, and water, which is used in the construction of roofing and beams, etc. Concrete becomes very hard and strong when it dries.

15. Nitrates, phosphates, metals, etc. are examples of which types of impurities in sewage? [S.S.C. Online MTS (T-I) 19.09.2017 (Shift-I)]

(a) Organic
(b) Inorganic
(c) Nutrients
(d) None of the above

Correct Answer: (b) Inorganic

Solution:Sewage can contain both organic and inorganic impurities. Nitrates, phosphates, metals, etc., are inorganic impurities, while urea, oil, sewage, urine, etc., are organic impurities, which are mainly found in sewage.

16. Molecules in solids [S.S.C. Online MTS (T-I) 20.09.2017 (Shift-II)]

(a) are free to move
(b) cannot move
(c) frequently swap places
(d) are circular in shape

Correct Answer: (b) cannot move

Solution:In solids, the molecules are strongly bound together by mutual intermolecular attraction and are not free for translational motion. Due to this, the volume and shape of the solid remain fixed.

17. The explosion of crackers is an example of [S.S.C. Online Graduate Level (T-I) 10.06.2019 (Shift-II)]

(a) Evaporation
(b) Decomposition
(c) Precipitation
(d) Combustion

Correct Answer: (d) Combustion

18. In solids, the molecules are strongly bound together by mutual intermolecular attraction and are not free for translational motion. Due to this, the volume and shape of the solid remain fixed. [S.S.C. Online MTS (T-I) 13.08.2019 (Shift-I)]

(a) Solid
(b) Plasma
(c) Liquid
(d) Bose-Einstein condensation

Correct Answer: (d) Bose-Einstein condensation

Solution:The new state of matter produced when a gas of very low density is cooled to a very low temperature (near absolute zero temperature) is called Bose-Einstein condensation. This state is possible only for boson particles (like photons, etc.).

19. Which of the following is a secondary pollutant? [S.S.C. Online MTS (T-I) 5.08.2019 (Shift-II)]

(a) Carbon Monoxide (CO)
(b) Fly ash
(c) Carbon dioxide
(d) Smog

Correct Answer: (d) Smog

Solution:Smog is called fog containing smoke. This is a secondary but serious pollution factor. Primary pollutants are those that are emitted directly from a source in the form of polluting causative gases. For example, carbon monoxide (CO), carbon dioxide (CO₂), and sulfur dioxide (SO₂) are the primary pollutants.

20. Which element has maximum presence in the sun? [S.S.C. Online Stenographer 14.09.2017 (Shift-I)]

(a) Hydrogen
(b) Oxygen
(c) Argon
(d) Krypton

Correct Answer: (a) Hydrogen

Solution:The largest amount of hydrogen gas is found in the Sun. The main source of the Sun’s energy is the vast reserves of hydrogen and helium present inside it. Energy is continuously produced in the Sun by the process of nuclear fusion.