Answer:
B. 
Explanation:
Assuming we are dealing with a perfect gas, we should use the perfect gas equation:

With T the temperature, V the volume, P the pressure, R the perfect gas constant and n the number of mol, we are going to use the subscripts i for the initial state when the gas has 20 cubic inches of volume and absolute pressure of 5 psi, and final state when the gas reaches 10 psi, so we have two equations:
(1)
(2)
Assuming the temperature and the number of moles remain constant (number of moles remain constant if we don't have a leak of gas) we should equate equations (1) and (2) because
,
and R is an universal constant:
, solving for 


Object weight varues on cellestial bodies due to the acceleration due to gravity acting on the body. the acc due to gravuty depend on the mass and radius of the cellestial body. Thus the weight varies on cellestian bodies
We start to see more off the dark side (waning) or more of the light side (waxing) the more of the dark side we see, the less moon there seems to be. The more light side, the more moon.