Chemistry - Study Mode

[#241] Type metal used in printing press is an alloy of
Correct Answer

(B) Lead and antimony

Explanation

Solution: Type metal, alloy of lead, antimony, and tin used to make type characters for printing. By varying the proportions of the metals, the desired properties are produced for different kinds of typecasting and printing processes.

[#242] Ultra purification of a metal is done by :
Correct Answer

(B) Zone melting

Explanation

Solution: When metals are required in a ultra pure state, the zone refining method is used. The principle-employed states that the impurities, which lower the melting point of a metal remain preferentially dissolved in the liquid phase and purer metal will emerge in the solid phase.

[#243] Brass gets discoloured in air due to constant exposure in presence of:
Correct Answer

(B) Hydrogen sulphide

Explanation

Solution: Brass gets discoloured in air because of Hydrogen sulphide. Transition elements are coloured. The brass is combination of Zn and Cu. But it is discoloured due to hydrogen sulphide in air.

[#244] Which of the following is not present in German silver?
Correct Answer

(C) Silver

Explanation

Solution: Silver is not present in german silver. German silver is an alloy of Copper, Nickel and Zinc.

[#245] Haloarenes are more stable than haloalkanes due to
Correct Answer

(A) Resonance effect

Explanation

Solution: Due to resonance, C-X bond in haloarenes acquire a double bond character which makes them more stable than haloalkanes.