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
Identify the products formed at the electrodes and describe the observations made during the electrolysis of: (a) molten lead(II) bromide (b) concentrated aqueous sodium chloride (c) dilute sulfuric acid using inert electrodes made of platinum or carbon/graphite
State that some of these substances are beneficial, including: (a) dissolved oxygen for aquatic life (b) some metal compounds provide essential minerals for life
Describe the general solubility rule for salts: (a) sodium, potassium and ammonium salts are soluble (b) nitrates are soluble (c) chlorides are soluble, except lead and silver (d) sulfates are soluble, except barium, calcium and lead (e) carbonates are insoluble, except sodium, potassium and ammonium (f) hydroxides are insoluble, except sodium, potassium, ammonium and calcium (partially)
