sir how can i solve this problem.

The rate of a first order reaction is 0.04 mol l^-1 s^-1 at 10 second and 0.03mol l^-1s^-1 at 20 second after initiation of the reaction. The half life period of the reaction is

1. 54.1s

2. 24.1s

3. 34.1s

4. 44.1 s

Please sir explain how the answer is 24.1 s . Please tell how to solve this. Thank u

Plz solve this problem.

Mechanism of a hypothetical reaction

X2+Y2 GIVES 2XY

(i)X2 GIVES X+X (FAST)

(ii) X+Y2 REV REACTION GIVES XY+Y (SLOW)

(iii)X+Y GIVES XY (FAST)

The overall order of the reaction is

(a) 0 (b)1.5 (c)1 (d) 2