Qualitative Analysis

To test for ........................., an effervescence which turns red litmus paper to blue evolves.

• hydrogen gas

• ammonia gas

• oxygen gas

• chlorine gas

What gas will be tested by placing a glowing wooden splinter into a test tube?

• Nitrogen

• Hydrogen

• Oxygen

• Carbon dioxide

How to test sulphur dioxide gas?

• Use damp blue litmus paper

• Test with acidified potassium manganate (VII) solution

• Use damp red litmus paper

• Test with glass rod dipped into concentrated ammonia solution

When an aqueous solution of a salt Q was tested with alkali solutions, the following observations was obtained.

A white precipitate that is insoluble in an excess of sodium hydroxide solution NaOH.

No change on the addition of ammonia solution, NH₃ to the salt solution.

What cation may be present in the salt?

Which of the following ion could give an insoluble white precipitate in excess sodium hydroxide solution, NaOH?

• Magnesium ion, Mg²⁺

• Aluminium ion, Al³⁺

• Lead (II) ion, Pb²⁺

• Zinc ion, Zn²⁺

What gas is formed when ammonium chloride is warmed with aqueous sodium hydroxide?

• Ammonia

• Chlorine

• Oxygen

• Hydrogen

Which ion, in aqueous solution, forms a white precipitate when dilute sulfuric acid is added?

• Ag+

• Ba2+

• Cu2+

• Fe2+

Aqueous sodium hydroxide reacts with a metal ion producing a coloured precipitate. This precipitate changes colour on standing. What is the ion present?

• Al3+

• Cu2+

• Fe2+

• Fe3+

What gas is formed when ammonium chloride is warmed with aqueous sodium hydroxide?

• Ammonia

• Chlorine

• Oxygen

• Hydrogen

A pale green solution X gives a green precipitate with excess aqueous sodium hydroxide. An alkaline gas is only given off when the mixture is warmed with aluminium powder. What ions does X contain?

• Ammonium and copper(II)

• Ammonium and iron(II)

• Nitrate and copper(II)

• Iron(II) and nitrate