Chemistry - Study Mode

[#396] The percentage of nitrogen present in ammonium sulphate is :
Correct Answer

(A) 27%

Explanation

Solution: Ammonium sulphate, (NH 4 )2SO 4 contains 21% nitrogen as ammonium cations, and 24% sulfur as sulfate anions. It is an inorganic salt which is most commonly used as a soil fertilizer.

[#397] The value of Avogadro Number is
Correct Answer

(B) 6.023 × 10 23

Explanation

Solution: The value of Avogadro Number is 6.023 × 10 23 .

[#398] Aqua regia is a 1 : 3 mixture, by volume, of
Correct Answer

(A) Conc. nitric acid and conc. hydrochloric acid

Explanation

Solution: Aqua regia or nitro-hydrochloric acid is a highly corrosive mixture of acids, a fuming yellow or red solution. The mixture is formed by freshly mixing concentrated nitric acid and hydrochloric acid, usually in a volume ratio of 1:3. It was named so because it can dissolve the so-called royal or noble metals, gold and platinum. However, titanium, iridium, ruthenium, tantalum, osmium, rhodium and a few other metals are capable of withstanding its corrosive properties. Aqua regia is also used in etching and in specific analytic procedures. It is also used in some laboratories to clean glassware of organic compounds and metal particles. This method is preferred over the “traditional” chromic acid bath for cleaning NMR tubes, because no traces of paramagnetic chromium can remain to later spoil acquired spectra.

[#399] Gold dissolves in
Correct Answer

(C) Aqua regia

Explanation

Solution: Gold dissolves in Aqua regia.

[#400] Nitric acid does not react with
Correct Answer

(A) Gold

Explanation

Solution: Some precious metals, such as pure gold and platinum-group metals do not react with nitric acid, though pure gold does react with aqua regia, a mixture of concentrated nitric acid and hydrochloric acid.