Miscellaneous And Useful Chemical Compounds (Part-I)

41. In arc welding, Argon is used because of its— [S.S.C. Online Graduate Level (T-I) 1.09.2016 (Shift-II)]

(a) Low reactivity with metal
(b) Ability to lower the melting point of the metal
(c) High flammability
(d) High calorific value

Correct Answer: (a) Low reactivity with metal

Solution:Argon is a noble gas. It is used in arc welding as it shows low reactivity with metals. During welding, there is no chemical change. But at high temperatures, the metal reacts with atmospheric oxygen to form oxides.

42. Which among the following is used to generate light to weld metals? [S.S.C. Online CHSL (T-I) 15.01.2017 (Shift-I)]

(a) Ethylene
(b) Acetylene
(c) Glycol
(d) Oxalic Acid

Correct Answer: (b) Acetylene

Solution:Acetylene is an organic gas with the chemical formula C₂H₂. This gas combines with oxygen to form oxyacetylene, which is used in welding metals.

43. Inert gases are: [S.S.C. Online Graduate Level (T-I) 1.09.2016 (Shift-II)]

(a) Miscible with water
(b) Not stable
(c) Chemically unreactive
(d) Chemically very active

Correct Answer: (c) Chemically unreactive

Solution:Inert gases are chemically inert. These are also called noble gases. They are members of group 18 of the periodic table. Like helium, argon, neon, etc., are inert gases.

44. Which among the following is a cation? [S.S.C. Online Graduate Level (T-I) 7.03.2020 (Shift-I)]

(a) Ammonium
(b) Fluoride
(c) Chloride
(d) Iodide

Correct Answer: (a) Ammonium

Solution:Ammonium (NH₄⁺) is a cation, while fluoride (F⁻), chloride (Cl⁻), and iodide (I⁻) are anions of halogens (group 17 elements).

45. Which one of the following statements is incorrect? [S.S.C. Online Graduate Level (T-I) 7.03.2020 (Shift-II)]

(a) Matter is made up of small particles.
(b) Evaporation causes cooling.
(c) Brass is a mixture of 30% Zinc and 70% Copper.
(d) The measurable unit of pressure is denoted in Metre.

Correct Answer: (d) The measurable unit of pressure is denoted in Metre.

Solution:The unit of pressure, i.e., force/area, is newton/m², and 1 newton/m² = 1 Pascal (Pa). Meter is the unit of distance. Hence, option (d) is wrong.

46. Name the densest stable element known on earth. [S.S.C. Online Graduate Level (T-I) 7.03.2020 (Shift-III)]

(a) Tungsten
(b) Osmium
(c) Aluminium
(d) Rhodium

Correct Answer: (b) Osmium

Solution:Osmium is the densest element ever known on Earth. The symbol for osmium is 'Os,' and the atomic number is 76. It is the transition element of the platinum group, which is very hard.

47. Which of the following noble gas is used as an anesthetic agent? [S.S.C. Online MTS (T-I) 2.08.2019 (Shift-II)]

(a) Xenon
(b) Argon
(c) Neon
(d) Helium

Correct Answer: (a) Xenon

Solution:Xenon gas is used as an anesthetic agent. The symbol of Xenon is 'Xe,' and the atomic number of Xenon is 54.

48. Which of the following is NOT a noble gas? [S.S.C. JE Mechanical Exam 22.03.2021 (Shift-I)]

(a) Argon
(b) Boron
(c) Neon
(d) Krypton

Correct Answer: (b) Boron

Solution:Noble gases are also called inert gases. Helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn) are inert gases. Boron is not an inert gas but a non-metallic element.

49. 'Rn' is the chemical symbol of which element? [S.S.C. Online C.P.O.S.I. (T-I) 5.07.2017 (Shift-III)]

(a) Radium
(b) Radon
(c) Rhenium
(d) Ruthenium

Correct Answer: (b) Radon

Solution:The 'Rn' symbol is the symbol for the element Radon. It is a colorless, tasteless gas. Radon is included in the category of noble gases, which is the 18th group of the periodic table. Its atomic number is 86, and its atomic weight is 222.

50. What is the name of the second lightest gas among all the gases? [C.P.O. S.I. 5.06.2016 (Shift-I)]

(a) Nitrogen
(b) Helium
(c) Hydrogen
(d) Oxygen

Correct Answer: (b) Helium

Solution:Of all the gases, the lightest gas is hydrogen, and the second lightest gas is helium. Radon is the heaviest gas.