The volumes of 50.0 milliliters of an ideal gas at STP increases to 100. milliliters?

Question

If the pressure remains constant, the new temperature must be

0, 100., 273, or 546 K

Answer 1

Use the ideal gas law, and find a way to cancel out everything that doesn't change.
PV = nRT

Rewrite that to:
V/T = nR/P (put all constant values on 1 side)
So:
V1/T1 = V2/T2 (nR/P is constant, so you can set 1 set of values against the other)

T1 = 273.15 K (0C, standard temperature)

50 mL / 273.15K = 100 mL / x
x = 100 mL * 273.15 K / 50mL
x = 576.3 K