Hi so im reviewing or our long test tomorrow on combined gas law and lussac's

Question

well here, combined gas law i find it (maybe ) confusing to do this one, because theres no right answers because it is a practice exercise..
what i know on combined gas law is that pressure is inversely proportional to the volume.pressure directly prporional to temperature. i got hooked up in these problem where all (P,V,T) are decreased ( the way i solved it )

here it is :

a gas measures 10 ml at 27 degrees celsius and 760 mm hg. what will be the volume of the gas at 15 degrees celsius and 750 mm hg ? help me please

Answer 1

combined gas law:

p1V1/T1=P2V2/T2

you are looking for V2

V2=P1/P2 * V1*T2/T1
= 760/750 * 10ml*(15+273)/(27+273)

Answer 2

760/750*10*285/300=9.595