Chemistry - Study Mode

[#316] 'Plaster of Paris' is made by partial dehydration of
Correct Answer

(B) Gypsum salt

Explanation

Solution: Plaster is a building material used for coating walls and ceilings. Plaster starts as a dry powder similar to mortar or cement and like those materials it is mixed with water to form a paste which liberates heat and then hardens. Unlike mortar and cement, plaster remains quite soft after setting, and can be easily manipulated with metal tools or even sandpaper. These characteristics make plaster suitable for a finishing, rather than a load-bearing material. The term plaster can refer to gypsum plaster (also known as plaster of Paris), lime plaster, or cement plaster. Plaster of Paris can be used to impregnate gauze bandages to make a sculpting material called modroc. It is used similarly to clay, as it is easily shaped when wet, yet sets into a resilient and lightweight structure.

[#317] Which one is the most reactive gaseous element?
Correct Answer

(D) Flourine

Explanation

Solution: Flourine is the most reactive gaseous element.

[#318] Which of the following metals occurs in free state ?
Correct Answer

(D) Lead

Explanation

Solution: A native metal is any metal that is found in its metallic form, either pure or as an alloy, in nature. Metals that can be found as native deposits singly and/or in alloys include aluminium, antimony, arsenic, bismuth, cadmium, chromium, cobalt, indium, iron, nickel, selenium, tantalum, tellurium, tin, titanium, and zinc, as well as two groups of metals: the gold group, and the platinum group. The gold group consists of gold, copper, lead, aluminium, mercury, and silver.

[#319] The “King of Metals” is :
Correct Answer

(A) Gold

Explanation

Solution: Gold, which is not only the most valuable of metals, but also is without its peer in freedom from alloy, is known as the king of metals. Luxurious, classy and beautiful, gold is the most classic and coveted jewelry metal of all. It is also the oldest precious metal known to man.

[#320] Which of the following metals is used in Space Crafts to withstand high temperatures ?
Correct Answer

(B) Ti

Explanation

Solution: Titanium alloy, which has high corrosion resistance, high specific strength, and good heat resistance, is used for different spacecraft parts including outer fuel tank sheathing and wings. It is extremely strong at high temperatures.