Arrange the following compounds in the increasing order of their property as indicated:
i. Acetaldehyde, acetone, di-tert-butyl ketone, methyl tert-butyl ketone (reactivity towards HCN).
ii. `CH_(3)CH_(2)CH(Br)COOH, CH_(3)CH(Br)CH_(2)COOH, (CH_(3))_(2)CHCOOH, CH_(3)CH_(2)CH_(2)COOH` (acidic strength).
iii. Benzoic acid, 4-nitrobenzoic acid, 3,4-dinitro-benzoic acid, 4-methoxybenzoic acid (acidic strength).

Explanation

i. More `bar e`-withdrowing group favours NA reaction (nucleophilic addition reaction), whereas `bar e`-donating group decreases reactivity towards NA reaction or reactivity towards HCN.
Decreasing order of NA reactivity:

So, Increasing order of reactivity towards HCN:
(IV)lt(III)lt(II)lt(I).
ii. a. EWG (`bar e`-withdrawing groups) increases the acidic strength, whereas EDG (`bar e`-donating groups) decreases the acidic strength.
b. Nearer is the EWG to the source `[(-COOH)` group], stronger is the acid, i.e., `alpha`-substituted halo acid stronger than `beta`- or `gamma`-substituted halo acid.
Decreasing order of acidic strength:

Increasing order of acidic strength:
(III)lt(IV)lt(II)lt(I).
iii. Decreasing order of acidic strength:

So, Increasing order of acidic strength:
(IV)lt(I)lt(II)lt(III).