Practice MCQ Questions and answers on Chemistry-GK

The mass percentage of oxygen in carbon dioxide is 72.7 %.

Number of 6.023 × 10²³ atoms present in one mole of a gas at STP is 6.023 × 10²³.

Ammonium sulphate, (NH₄)2SO₄ 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.

The value of Avogadro Number is 6.023 × 10²³.

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.

Gold dissolves in Aqua regia.

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.

Nitrogen enters water in numerous forms, including both inorganic and organic forms. The primary inorganic forms of N are ammonia, ammonium, nitrate, and nitrite. Commonly found is nitrite.

Aqua regia or nitro-hydrochloric acid is a highly corrosive mixture of acids which is formed by freshly mixing concentrated Nitric acid (HNO₃) and Hydrochloric acid (HCl), optimally in a volume ratio of 1 : 3. It is used in dissolving gold.

Aqua regia is a mixture of concentrated hydrochloric acid and nitric acid in the ratio of 3:1, and can dissolve noble metals like gold.