Question

when a gas filled in a closed vessel is heated to 1 degree Celsius ,its pressure increased by 0.4percent .the initially temperature of the gas was?

Answer 1

Let P2 = 1.004 P1 ..... A 0.4% increase in P 
Let T2 = T1 + 1 ........... See note below 

P1V1/T1 = P2V2/T2 ..... combined gas law 
P1/T1 = P2/T2 ............... Assume V remains constant. 
T1 = P1T2 / P2 .............. solve for T1 
T1 = P1(T1+1) / (1.004P1) 
T1 = (T1+1) / 1.004 
1.004T1 = T1 + 1 
1.004T1 - T1 = 1 
0.004T1 = 1 
T1 = 1 / 0.004 
T1 = 250K 
Hope any 1 of the 2 helps you out

Answer 2

Let P2 = 1.004 P1 ..... A 0.4% increase in P 

Let T2 = T1 + 1 ........... See note below 

P1V1/T1 = P2V2/T2 ..... combined gas law 

P1/T1 = P2/T2 ............... Assume V remains constant. 

T1 = P1T2 / P2 .............. solve for T1 

T1 = P1(T1+1) / (1.004P1) 

T1 = (T1+1) / 1.004 

1.004T1 = T1 + 1 

1.004T1 - T1 = 1 

0.004T1 = 1 

T1 = 1 / 0.004 

T1 = 250K