.500 l of gas at STP is changed to 150c at the same volume. Whats the new pressure

Answer 1

PV = n R T
n R and V are constant here
P = (nR/V) T
or
P/T is constant
T initial = 273 Kelvin
Tfinal = 423 K
P/423 = Pstp/273
P = (1 atm or 10^5 Pascals)* (423/273)

Answer 2

the pressure is proportional to the absolute (Kelvin) temperature

(new pressure) / (old pressure) = (new temperature) / (old temperature)