A 0.1 M solution of a weak monobasic acid (K_a=1.0x10^-5) is diluted to 0.025 M at 298 K (use alphall1, log2=0.301). Select the correct statement(s).

The degree of ionisation doubles.

The pH increases by about 0.30.

[H+] becomes half of its original value.

The degree of ionisation doubles.

The pH increases by about 0.30.

[H+] becomes half of its original value.

K_a becomes half of its original value.

JEE Advanced levelOne or more correct optionsDifficulty 3 of 3ie103

A $0.1 M$ solution of a weak monobasic acid ( $K_{a} = 1.0 \times 1 0^{- 5}$ ) is diluted to $0.025 M$ at 298 K (use $α ≪ 1$ , $lo g 2 = 0.301$ ). Select the correct statement(s).

[H X^{+}] = K_{a} c

1 0^{- 3} \to 5 \times 1 0^{- 4} M

(half), so pH rises by

lo g 2 = 0.30

α = K_{a} / c

goes from

0.01

0.02

(doubles).

K_{a}

depends only on temperature and stays constant.