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
Describe how paper chromatography is used to separate mixtures of soluble substances, using a suitable solvent
Identify redox reactions by changes in oxidation number using: (a) the oxidation number of elements in their uncombined state is zero (b) the oxidation number of a monatomic ion is the same as the charge on the ion (c) the sum of the oxidation numbers in a compound is zero (d) the sum of the oxidation numbers in an ion is equal to the charge on the ion
Describe tests using aqueous sodium hydroxide and aqueous ammonia to identify the aqueous cations: (a) aluminium, Al^3+ (b) ammonium, NH4^+ (c) calcium, Ca^2+ (d) chromium(III), Cr^3+ (e) copper(II), Cu^2+ (f) iron(II), Fe^2+ (g) iron(III), Fe^3+ (h) zinc, Zn^2+
