1. The boiling points of some compounds of hydrogen with some elements in groups 4 and 6 of the periodic table are given below

Compound	Boiling point(°C)	Compound	Boiling point(°C)
CH4	-164.0	H2O	100.0
SiH4	-112.0	H2S	-61.0

(a) Which of the compounds CH4and SiH4 has the stronger intermolecular forces? (1 mark)
(b) Explain why the boiling point of H2O and H2S show different trends from that of CH4 and SiH4.(2 marks)


2. (a) Study the table below and complete it.(W- and X4+ are not the actual symbols of the ions)

Ion	Number of Protons	Number of neutrons	Mass Number	Electron Arrangement
W-		20		2.8.8
X4+	14		28

(b) The atomic numbers of Na and Mg are 11 and 12 respectively. Which of the element has higher ionization energy?  Explain.(2 marks)

3. (a)Using electrons in the outermost energy level, draw the dot (.) and cross (x) diagram for the molecules H2O and C2H4. (H = 1, C = 6, O = 8) (2 marks)
(i)H2O
(ii)C2H4
(b)The formula of a complex ion is [Zn(NH3)4]2+. Name the type of bond that is likely to exist between zinc and ammonia in the complex ion. (1 mark)


4. he atomic numbers of phosphorus, sulphur and potassium are 15, 16 and 19 respectively. The formulae of their ions are P3-, S2- and K+. These ions have the same number of electrons.
(a)Write the electron arrangement for the ions.(1 mark)
(b)Arrange the ions in the order of increasing ionic radius starting with the smallest. Give a reason for the order.(2 marks)