In the question we are given the length of the pendulum, l = 1 m

Amplitude of the pendulum, $A = 2 \text{ cm}$
And the time period of this pendulum, $T = 5$ seconds.
We have to find the time period of this pendulum, when its amplitude becomes 4 cm .
We know, time period of a simple pendulum is given by the equation, $T = 2 \pi \sqrt{\frac{l}{g}}$ , where ' 1 ' is the length of the pendulum and ' g ' is acceleration due to gravity.
From this equation, it is clear that the time period of a simple pendulum does not depend on its amplitude.
In the question, we change the amplitude of the pendulum from 2 cm to 4 cm . Length of the pendulum remains the same and acceleration due to gravity; ' g ' is a constant.
Therefore, the time period of the pendulum when its amplitude = 4 cm , length ' 1 ' = 1 m will be 5 seconds.