20 cubic inches of a gas with an absolute pressure of 5 psi is compressed until its pressure reaches 10 psi. what is the new volume of the gas? (assume that there's no change in temperature.

Initial volume of the gas (V1) = 10 inches^3
Initial pressure (P1) = 5 psi
Final pressure after compression of the gas (P1) = 10 psi
Let us assume the final volume of the gas (V2) = x
According to Boyle's Gas law, the pressure and volume of a gas remains constant under ideal condition. Then
P1V1= P2V2
5 * 10 = 10 * x
50 = 10x
x = 50/10
   = 5 cubic inches
So the volume of the gas after it was compressed was 5 cubic inches. I hope the procedure is clear enough for you to understand.

B. a circuit. i think