An ideal gas is compressed isothermally to one-third of its initial volume. The resulting pressure will be

(A) three times as large as the initial value.
(B) less than three times as large as the initial value.
(C) more than three times as large as the initial value.
(D) equal to the initial value.

(A) three times as large as the initial value.

Explanation:

Boyle law states that the pressure is inversely proportional to volume if we kept the temperature constant.

       (1)

here and are the initial pressure and volume.

and are the final pressure and volume respectively.

now

by putting these values in equation 1.

hence it is proved that " if the volume is decreased to one third of its original value then the pressure will be three times larger then its initial value".