Tests for anions for IGCSE and O Level Chemistry

What is the expected observation when testing for carbonate ions using dilute acid and limewater?

• Limewater turns blue.

• Limewater turns milky.

• Limewater turns yellow.

• Limewater remains clear.

Why is nitric acid added before barium nitrate when testing for sulfate ions?

• To increase the solubility of barium sulfate.

• To ensure all sulfate ions react.

• To remove any interfering carbonate ions.

• To change the color of the solution.

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What color precipitate is formed when silver nitrate is added to a solution containing bromide ions, after adding nitric acid?

• White

• Cream

• Yellow

• No precipitate

What gas is produced when nitrate ions are heated with aluminum foil and sodium hydroxide, and how is it identified?

• Carbon dioxide, turns limewater milky.

• Hydrogen, extinguishes a lit splint with a pop sound.

• Ammonia, turns damp red litmus paper blue.

• Oxygen, relights a glowing splint.

How is the presence of sulfur dioxide gas, produced from sulfite ions, confirmed?

• It turns limewater milky.

• It turns damp red litmus paper blue.

• It decolorizes acidified potassium permanganate from purple to colorless.

• It relights a glowing splint.