Qualitative Analysis

Which cation gives a red-brown precipitate with aq. NaOH?

• Fe²⁺

• Fe³⁺

Which cation gives a light blue precipitate with aqueous sodium hydroxide?

• Cr³⁺

• Cu²⁺

Which cation gives a white precipitate insoluble in excess with NaOH?

• Al³⁺

• Zn²⁺

• Ca²⁺

All of the following salts are soluble except

• lead (II) nitrate

• sodium carbonate

• magnesium chloride

• Barium sulfate

Salt X is added to sodium hydroxide solution and the mixture is heated. The gas evolved turns damp red litmus paper blue. What ion is present in salt X?

• Ammonium ion

• Sulfate ion

• Carbonate ion

NaOH is added to an unknown solution. A strong pungent smell is given off. The formula of the ion is

• Cl^-

• I^-

• NH₄⁺

Add water to anhydrous copper (II) sulfate. The colour changes from

• blue to white

• white to blue

How to test for chlorine gas?

• Turns purple acidified potassium manganate (VII) colourless

• Bleaches damp blue litmus paper

When we test for nitrate ion, which gas is evolved?

• Nitrogen dioxide

• Ammonium

• Ammonia

Which two reagents are required for testing of aqueous cations?

• NaOH & Al

• NaOH and NH₃

• NaOH & HNO₃