The apparatus below was used for the preparation of iron (III) chloride in the laboratory. Study it and use it to answer the questions that follow.

a) Why is it preferred to use calcium oxide rather than calcium chloride in the guard tube? (2 Marks)

b) What property of iron (III) chloride makes it possible to be collected as shown in the diagram? (1 Mark)

Magnesium reacts by losing its 2 valence electrons. How does its 1st and 2nd ionization energy compare? Explain (2 Marks)

A luminous flame produces bright yellow light. Explain (1 Mark)

The following apparatus was set up to investigate the percentage of oxygen in air by slowly passing 100cm³ of air from syringe A to syringe B and then back until the volume of air remained constant. Study it and use it to answer the questions that follow.

a) Identify the mistake in the setup (1 Mark)

b) Why was the air moved slowly from syringe A to syringe B and vice versa? (1 Mark)

c) Write an equation for the reaction that took place in the combustion tube after the mistake was corrected (1 Mark)

Calculate the number of sulphate ions in 150cm³ of 0.1M aluminium sulphate, Al2(SO4)₃ (3 Marks)   (L = 6.023 × 10²³)

20cm³ of a solution containing 2.7g/dm³ of an alkali XOH completely reacted with 25cm³ of 0.045M sulphuric (VI) acid. Calculate the relative atomic mass of element X (O = 16, H = 1) (3 Marks)

The electron arrangement of ions W³⁺ and Z^2- are 2.8 and 2.8.8 respectively.

a) In which groups do elements W and Z belong?   (1 Mark)

b) Write the formula of the compound that would be formed between W and Z   (1 Mark)

Calculate the volume of oxygen produced when 10g of silver nitrate was completely decomposed by heating at standard temperature and pressure
(Ag = 108, N = 14, O = 16, Molar gas volume at s.t.p. = 22400cm³) (3 Marks)

400cm³ of a gas D diffuses through a porous plug in 50 seconds, while 600cm³ of oxygen gas diffuses from the same apparatus in 30 seconds. Calculate the relative molecular mass of gas D. (O = 16) (2 Marks)

The information in the table below relates to the physical properties of the chlorides of certain elements.

a) Select two chlorides that are liquid at room temperature (2 Marks)

b) Explain why AlCl₃ has a much lower melting point than MgCl₂, although both aluminium and magnesium are metals. (2 Marks)