NEET Practice Questions (MCQs) with Answers & Solutions

(c) Lead present as impurity in the silver obtained by argentiferous lead is purified by cupellation.

(d) Purification of Bauxite involves Baeyer's process, Hall's process and Serpek's process only.

(d) Rock salt is NaCl.

karnallite (also carnalite) is an evaporite mineral, a hydrated potassium magnesium chloride with formula KMgCl₃·6(H₂O).

(b) VIA group member or oxygen family is known as chalcogens.

(b) Mond's process is used for the purification of Ni.

(b) Silver is recovered from the alloy (lead-silver alloy) by cupellation.

Cupellation is a refining process in metallurgy, where ores or alloyed metals are treated under very high temperatures and have controlled operations to separate noble metals, like gold and silver, from base metals like lead, copper, zinc, arsenic, antimony or bismuth, present in the ore.^[1][2][3] The process is based on the principle that precious metals do not oxidise or react chemically, unlike the base metals; so when they are heated at high temperatures, the precious metals remain apart and the others react forming slags or other compounds.^[4]

Since the Early Bronze Age, the process was used to obtain silver from smelted lead ores.^[5] By the Middle Ages and the Renaissance, cupellation was one of the most common processes for refining precious metals. By then, fire assays were used for assaying minerals, that is, testing fresh metals such as lead and recycled metals to know their purity for jewellery and coin making. Cupellation is still in use today.^[4][6]

(c) Chile saltpetre is NaNO₃.

(b) It is a fact.

A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. Blast refers to the combustion air being "forced" or supplied above atmospheric pressure.^[1]

In a blast furnace, fuel (coke), ores, and flux (limestone) are continuously supplied through the top of the furnace, while a hot blast of air (sometimes with oxygen enrichment) is blown into the lower section of the furnace through a series of pipes called tuyeres, so that the chemical reactions take place throughout the furnace as the material falls downward. The end products are usually molten metal and slag phases tapped from the bottom, and waste gases (flue gas) exiting from the top of the furnace. The downward flow of the ore and flux in contact with an upflow of hot, carbon monoxide-rich combustion gases is a countercurrent exchange and chemical reaction process.^[2]

(d) Purification of Hg,  Sn and Bi involves liquation.

Liquation, technique for separating constituents of an ore, a metal, or an alloy by partial melting. When the material is heated to a temperature where one of the constituents melts and the other remains solid, the liquid constituent can be drained off. It was formerly used for extracting antimonyminerals from ore and for separating silver from copper with the use of lead as a solvent. It is still used in some refining of tin.