Question

If 50.75 g of a gas occupies 10.0 l at stp, 129.3 g of the gas will occupy __________ l at stp.

Answer 1

Use PV = mRT/M and solve for R. R = PVM/RT. Since you have the same gas under two sets of conditions then you can write 
P1V1M1/m1T1 = P2V2M2/m2T2 
Since P, M and T are constant, the equation becomes 
V1/m1 = V2/m2 
Now plug in your values and solve for V2

Answer 2

Answer: 25.5 L

Explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 Liters at STP and contains avogadro's number $6.023\times 10^{23}$ of particles.

We are given:

50.75 g of a gas occupies = 10.0 L at STP

Thus 129.3 g  of a gas occupies =$\frac{10}{50.75}\times 129.3=25.5L$ at STP

Thus 129.3 g of gas will occupy 25.5 L at STP.