Question

1 A certain mass of a gas occupies volume 2 litre at STP keeping the pressure constant at what temperature would the gas occupies volume 4L

2 one litre of unknown gas weighs 1.25 gram at ntp which of the following gas pretend to be the above data

Answer 1

Given: Volume = 2L
​At STP, Pressure, P1 = 1 atm and Temperature, T1 = 273 K
Final Volume, V2 = 4L
To find: Final temperature, T2
​Solve: As we know
PV = nRT
Now, for given number of moles at constant pressure volume is directly proportional to temperature. We can write as

V2/V1 =T2/T1

4/2 =T2/273

T2=273*2
=546 K

Temperature in degree Celsius = 546-273
= 273 degree celcius

2.here i take option as arbitrary because you don't give me options
Since 1 mole of a gas is contained in 22 litres.
Then there is 1/22 = 0.04545... moles present

Using the equation ,
moles = mass(g) / Mr
Then it follows
Mr = mass(g) / Moles
Mr = 1.25g / 0.04545...
Mr = 27.5 ( Relative Molecular mass of the gas).

Mr's of
CO2 = 12 + 16 + 16 = 44
CO = 12 + 16 = 28
O2 = 16 + 16 = 32
SO2 = 32 + 16 + 16 = 64

Since we have an Mr of 27,5' , then the gas could be 'CO' ( Carbon Monoxide)