A gas occupies a volume of 10cm3 at 100kPa. If the pressure is increased to 200kPa, What is the new volume if the temperature remains constant at 27°C.

Answer 1

Dr Bob showed you how to do these in two problems below.
The only thing I might add is remember that you need to use degrees Kelvin in your P V = n R T calculations which is degrees Centigrade + 273
P1 V1/T1 = P2 V2/T2
Here T is constant so
P1 V1 = P2 V2