Question

Three metal compounds, P, Q and R, are heated using a Bunsen burner. The results are shown.
P colourless gas produced, which relights a glowing splint
Q colourless gas produced, which turns limewater milky
R no reaction
Which row shows the identity of P, Q and R?

Answer 1

Answer:

à is the correct answer

Answer 2

Answer:

P. Potassium nitrate

Q. Magnesium carbonate

R. Potassium carbonate

Explanation:

P. Potassium nitrate

• Potassium nitrate decomposes into potassium nitrite and oxygen when heated.
• Nitric acid is formed when potassium nitrate combines with hydrochloric acid.
• To distil the nitric acid, add concentrated sulfuric acid to dry potassium nitrate and melt the mixture over heat.

Q. Magnesium carbonate

• When magnesium oxide is burned, it turns into a white powder.
• Magnesium provides two electrons to oxygen atoms to produce this powdered substance.

R. Potassium carbonate

• It is water soluble.
• This acid compound will not fizz or burst. It appears to have no effect.

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