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
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
recall the reactions (reagents and conditions) by which alkanes can be produced: (a) addition of hydrogen to an alkene in a hydrogenation reaction, \( H_2(g) \) and Pt/Ni catalyst and heat (b) cracking of a longer chain alkane, heat with \( Al_2O_3 \)
deduce the presence of a CH\(_3\)CO– group in an aldehyde or ketone, CH\(_3\)CO–R, from its reaction with alkaline I\(_2\)(aq) to form a yellow precipitate of tri-lodomethene and an ion, \( RCO_2^-\)
