Acids and Bases Chemistry

This option is correct and can be explained as follows:
Basicity is defined as the number of replaceable H atoms. Since phosphorus acid H₃PO₃ has only two replaceable atoms its basicity is two.

This option is correct because for strong acids (which are completely ionized) only concentration is the measure of strength but for weak acids (which are incompletely ionized) both degree of ionization (K_a) and concentration is required.

This option is correct as we know that aprotic solvents do not have replaceable hydrogen in them and are non-polar or very weakly polar non-dissociated liquid which do not solvate strongly. Like Hydrocarbons, C₆H₆ maintains all these properties and is an aprotic solvent.

This option is correct as we know that the strongest conjugate base will have a weak conjugate acid. For the given option CH₃COOH will be the conjugate acid which is a weak acid  among the other options.

This option is correct as we know that acids always donate a proton and in the given reaction NH₃ changes to NaNH₂ which contains NH₂^- ion. This means that NH₃ has donated a proton to Na. Hence, acts as an acid.

This answer is correct and can be explained as follows:
Sulphanillic acid contains SO₃H and NH₂ group. The SO₃H group is capable of donating H⁺ and it acts as an arrhenius acid while nitrogen in NH₂ group contains a lone pair of electrons and acts as a Lewis Base by donating it. Hence, sulphanillic acid is both an arrhenius acid and Lewis Base.

This option is correct as we know that higher the value of K_a higher will be the strength of the acid. Hence, in the given question the highest value of K_a is for HCOOH followed by CH₃COOH, HCN, HS^- etc.

This option is correct because glycine contains both acidic and basic groups and it undergoes mutual neutralization to form zwitter ions as shown below by the reaction:
NH₂-CH₂-COOH → N⁺H₃-CH₂-COO^-

This option is correct because we know that lower will be the acidic strength higher will the basic strength of the conjugate base, since conjugate acids of the following bases follow the order of strength as
HCl > HF > CH₃COOH > H₂CO₃ > H₂O.

This option is correct because we know that soft acid includes ions of heavier transition metals and those in lower oxidation states which are large sized and their outer orbits are easily distorted. Since cadmium is also from heavier transition metals having outer orbits which are easily distorted due to inert pair effect, it is a soft acid.