Q50. Identify the INCORRECT statement about stainless steel.
[SSC JE (Mechanical Engineering), 6 November 2024]
(A) Stainless steels are alloy steels.
(B) Stainless steel contains chromium.
(C) Stainless steels are non-ferrous steels.
(D) Stainless steels resist corrosion.
𝐀𝐧𝐬𝐰𝐞𝐫: (C) Stainless steels are non-ferrous steels.
Explanation: Stainless steel is a ferrous alloy because iron is its principal constituent. Chromium, usually at least about 10.5%, allows a protective oxide film to form on its surface. This passive layer gives stainless steel useful corrosion resistance.
Q49. According to Ministry of Mines data, the largest resources of primary gold ore are located in which Indian state?
[SSC GD Constable, 24 February 2024, Shift 2]
(A) West Bengal
(B) Bihar
(C) Rajasthan
(D) Karnataka
𝐀𝐧𝐬𝐰𝐞𝐫: (B) Bihar
Explanation: In the resource inventory referred to by the examination, Bihar had the largest estimated primary gold-ore resources. This concerns geological resource estimates rather than actual gold production; Karnataka has historically dominated primary gold mining in India.
Q48. Which is the reducing agent in the thermite reaction used for repairing railway tracks?
[WBCS (Executive) Preliminary Examination, 2023]
(A) Iron oxide
(B) Aluminium metal
(C) Aluminium oxide
(D) Iron metal
𝐀𝐧𝐬𝐰𝐞𝐫: (B) Aluminium metal
Explanation: Aluminium removes oxygen from iron(III) oxide in the highly exothermic thermite reaction: Fe₂O₃ + 2Al → 2Fe + Al₂O₃. The reaction releases enough heat to produce molten iron, which can be used to weld railway rails.
Q47. The most important ore of aluminium is
[SSC CGL, 19 July 2023, Shift 1 (memory-based)]
(A) Bauxite
(B) Calamine
(C) Calcite
(D) Galena
𝐀𝐧𝐬𝐰𝐞𝐫: (A) Bauxite
Explanation: Bauxite consists mainly of aluminium hydroxide minerals with other impurities. Industrial processing separates alumina from the ore, and electrolysis then yields aluminium metal. Calamine is associated with zinc; galena with lead; calcite is calcium carbonate.
Q46. Which s-block element is a silvery metal used in alloys with copper or nickel for gyroscopes, springs, electrical contacts and non-sparking equipment?
[SSC CHSL Tier I, 2 August 2023, Shift 4]
(A) Beryllium
(B) Rubidium
(C) Francium
(D) Caesium
𝐀𝐧𝐬𝐰𝐞𝐫: (A) Beryllium
Explanation: Beryllium is a light, stiff metal. Copper–beryllium alloys combine strength, springiness and non-sparking performance, making them useful in precision components and some specialist tools. Beryllium dust is hazardous, so its industrial handling requires strict safeguards.
Q45. Match the approximate mass percentages in Earth’s crust:
i. Oxygen;
ii. Silicon;
iii. Aluminium;
iv. Iron,
with
a. 8%;
b. 28%;
c. 47%;
d. 5%.
[SSC Stenographer, 12 October 2023, Shift 1]
(A) i-a, ii-b, iii-c, iv-d
(B) i-c, ii-a, iii-b, iv-d
(C) i-c, ii-b, iii-a, iv-d
(D) i-b, ii-a, iii-c, iv-d
𝐀𝐧𝐬𝐰𝐞𝐫: (C) i-c, ii-b, iii-a, iv-d
Explanation: Oxygen makes up approximately 47% of the Earth’s crust by mass, followed by silicon at 28%, aluminium at 8% and iron at 5%. Aluminium is consequently the most abundant metallic element in the crust.
Q44. According to the Indian Minerals Yearbook 2020, which state had the highest manganese production in India?
[SSC CHSL Tier I, 3 August 2023, Shift 1]
(A) Karnataka
(B) Madhya Pradesh
(C) Odisha
(D) Maharashtra
𝐀𝐧𝐬𝐰𝐞𝐫: (B) Madhya Pradesh
Explanation: The cited Indian Minerals Yearbook identifies Madhya Pradesh as the leading manganese producer for the reference period. Manganese is essential in steelmaking as an alloying and deoxidizing element, and it is also used in battery chemistry.
Q43. Which Indian region has high-grade iron-ore deposits?
[SSC CHSL Tier I, 17 August 2023, Shift 3]
(A) Western Rajasthan
(B) Southern Punjab
(C) Eastern Uttar Pradesh
(D) Northern Odisha
𝐀𝐧𝐬𝐰𝐞𝐫: (D) Northern Odisha
Explanation: Northern Odisha contains extensive high-grade hematite deposits, especially near Keonjhar, Mayurbhanj and Sundargarh. Hematite is iron(III) oxide, Fe₂O₃. Ore from this belt has long supplied blast furnaces and steel plants in eastern India.
Q42. Which of the following has the highest electrical resistivity?
[SSC CGL Tier I, 17 July 2023, Shift 1]
(A) Silver
(B) Nichrome
(C) Chromium
(D) Iron
𝐀𝐧𝐬𝐰𝐞𝐫: (B) Nichrome
Explanation: Nichrome is an alloy, mainly of nickel and chromium, with much higher electrical resistivity than silver and common structural metals. Its resistance to oxidation and heat makes it suitable for electric heating coils and resistance wires.
Q41. Which metal is always a component of an amalgam?
[SSC MTS 2022 examination, 15 June 2023, Shift 1]
(A) Strontium
(B) Mercury
(C) Zinc
(D) Aluminium
𝐀𝐧𝐬𝐰𝐞𝐫: (B) Mercury
Explanation: An amalgam is an alloy containing mercury combined with another metal. Traditional dental amalgam, for example, mixes mercury with powdered silver, tin and copper alloys. Mercury distinguishes amalgams from other common industrial metal mixtures.
