Older MCQs might not have the typical A, B, C,
D
choices. They
have choices 1, 2, 3, and a combination of them is the answer. Below is the key that maps such
combinations to the answer.
A
1, 2 and 3 are correct
B
1 and 2 only are correct
C
2 and 3 only are correct
D
1 only is correct
(a) describe hydrogen bonding, limited to molecules containing N–H and O–H groups, including ammonia and water as simple examples (b) use the concept of hydrogen bonding to explain the anomalous properties of H\(_2\)O (ice and water): • its relatively high melting and boiling points • its relatively high surface tension • the density of the solid ice compared with the liquid water
define covalent bonding as electrostatic attraction between the nuclei of two atoms and a shared pair of electrons (a) describe covalent bonding in molecules including: - hydrogen, H\(_2\) - oxygen, O\(_2\) - nitrogen, N\(_2\) - chlorine, Cl\(_2\) - hydrogen chloride, HCl - carbon dioxide, CO\(_2\) - ammonia, NH\(_3\) - methane, CH\(_4\) - ethane, C\(_2\)H\(_6\) - ethene, C\(_2\)H\(_4\) (b) understand that elements in period 3 can expand their octet including in the compounds sulfur dioxide, SO\(_2\), phosphorus pentachloride, PCl\(_5\), and sulfur hexafluoride, SF\(_6\) (c) describe coordinate (dative covalent) bonding, including in the reaction between ammonia and hydrogen chloride gases to form the ammonium ion, NH\(_4^+\), and in the Al\(_2\)Cl\(_6\) molecule
