If the pressure of a sample of gas is doubled at constant temperature, what happens to the volume of the gas? a) the volume doubles. b) the volume is halved. c) the volume quadruples. d) the volume remains the same.

according to ideal gas equation , we have

PV = n RT

where P = pressure , V = Volume , n = number of moles , R = gas constant and

T = temperature

the formula can be rearranged as

T = PV/(nR)

at constant temperature , the formula can be reformed as

T₁ = T₂

P₁V₁/(nR) = P₂V₂/(nR)

hence

P₁V₁ = P₂V₂

where

P₁ = initial pressure

P₂ = final pressure = 2 P₁

V₁ = initial volume

V₂ = final volume

P₁V₁ = (2 P₁ )V₂

V₁ = (2) V₂

V₂ = V₁ /2

hence the Volume is halved

its B on USATestPrep

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.