Home / AS & A Level Chemistry 9.2 Periodicity of chemical properties of the elements in Period 3 Exam Style Practice Questions Paper 1
A student investigated the chloride of a Period 3 element. This is what the student wrote down as the observations.
What can be deduced from these observations?
Correct Answer: \( \boxed{\mathrm{A}} \)
The observations are inconsistent with any Period 3 chloride.
Therefore, at least one of the recorded observations must be incorrect.
Hence, the correct answer is (A).
Element E is in Period 3. It forms a chloride which reacts with a small amount of water to produce a white precipitate and steamy fumes. This precipitate is soluble in \(\mathrm{NaOH(aq)}\) and in \(\mathrm{HCl(aq)}\).
What is element E?
Correct Answer: \( \boxed{\mathrm{B}} \)
Aluminium chloride hydrolyses in a small amount of water:
\(\mathrm{AlCl_3+3H_2O\rightarrow Al(OH)_3+3HCl}\)
The white precipitate is \(\mathrm{Al(OH)_3}\), while hydrogen chloride produces steamy fumes.
Aluminium hydroxide is amphoteric, so it dissolves in both aqueous sodium hydroxide and hydrochloric acid.
Therefore, the correct answer is (B).
Compound X is an oxide of a Period 3 element.
Compound X is a white solid at \(25^\circ\mathrm{C}\). It reacts with water to form an acidic solution.
What is compound X?
Correct Answer: \( \boxed{\mathrm{D}} \)
Phosphorus(V) oxide is a white solid that reacts vigorously with water to form phosphoric acid:
\(\mathrm{P_4O_{10}+6H_2O\rightarrow4H_3PO_4}\)
Aluminium oxide is amphoteric, silicon dioxide does not react with water, and sulfur dioxide is a gas at room temperature.
Therefore, the correct answer is (D).