acids bases and salts

1. An example of an acidic oxide is:

• MgO

• CO₂

• BaO

• Na₂O

After a compound X was added to water, the pH using indicator paper was less than 7. The resulting solution was added to some calcium carbonate and it was noted that effervescence took place. What could compound X be?

• HNO₃

• MgO

• Na₂O

• CaO

A solution was added to some ammonium chloride then heated. A gas which had a pungent smell and turned moist red litmus blue was produced. Which of the following could have been present in the original solution?

• Hydrochloric acid

• vinegar

• potassium hydroxide

• sodium chloride

Statements 1 to 4 represent different steps in the preparation of lead iodide. Which of the following is the best sequence for synthesizing lead iodide?

1. Mix lead nitrate and potassium iodide

2. Dry

3. Filter

4. Mix lead sulphate and potassium iodide

• 1, 3, 2

• 4, 3, 2

• 1, 4, 2

• 4, 2, 3

1. A salt was being prepared by adding an acid to a carbonate. However, after a while, the reaction ceased and a precipitate began to form without all of the carbonate reacting. Which of the following pairs of acid and carbonate

• CaCO₃, H₂SO₄

• CuCO₃, HCl

• BaCO₃, HNO₃

• Na₂CO₃, H₂SO₄

Sodium hydroxide was added to a solution and it was noticed that a white precipitate was formed at first then dissolved in excess. On adding aqueous ammonia to a fresh sample of the solution, a white precipitate was formed which did not dissolve in excess. Which ion could have been present in the solution?

• Fe²⁺

• Al³⁺

• Zn²⁺

• Ca²⁺

What is the best way of making zinc carbonate?

• Shake solid zinc hydroxide with aqueous sodium carbonate

• Shake solid zinc sulphate with and solid calcium carbonate with water

• Shake solid zinc sulphate with water and add aqueous sodium carbonate

• Shake aqueous zinc sulphate with solid calcium hydroxide and bubble in carbon dioxide

Which property does hydrochloric acid have?

• It liberates ammonia from ammonium salts

• It reacts with any base to give a salt

• It reacts with any metal to give hydrogen

• It turns red litmus paper blue

Aqueous ammonia was added to a solution of a salt. A blue precipitate was formed which dissolved to give a deep blue solution in excess ammonia. Which of the following ions could be present?

• Cu²⁺

• Fe²⁺

• Pb²⁺

• Fe³⁺

Which of the following is the best description of a salt?

• Forms when two metals react

• Forms when a carbonate reacts with sodium hydroxide

• Forms when all or part of the hydrogen ions in an acid is replaced

• Forms when two alkali reacts