Is the oscillation of a simple pendulum at the centre of the earth possible?

The length of the seconds pendulum is decreased by $0.3 \ cm$ when it is shifted from place $A$ to place $B$. If the acceleration due to gravity at place $A$ is $981 \ cm/s^2$,the acceleration due to gravity at place $B$ is $($ Take $\pi^2 = 10$ $)$ (in $cm/s^2$)

$A$ pendulum oscillates simple harmonically if and only if:
$I$. The size of the bob of the pendulum is negligible in comparison with the length of the pendulum.
$II$. The angular amplitude is less than $10^{\circ}$.
Choose the correct option.

Two pendulums begin to swing simultaneously. If the ratio of the frequency of oscillations of the two is $7 : 8$,then the ratio of lengths of the two pendulums will be

$A$ positively charged pendulum is oscillating in a uniform electric field pointing upwards. How does its time period compare to the time period when it oscillates without an electric field?

The time period of a simple pendulum inside a stationary lift is $\sqrt{3} \ s$. When the lift moves upwards with an acceleration $g/3$,the new time period will be ($g=$ acceleration due to gravity).