# The mass of molecule A is twice the mass of molecule B. The rms speed of A is twice the rms speed of B. If two samples of A and B contain same numbe

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The mass of molecule A is twice the mass of molecule B. The rms speed of A is twice the rms speed of B. If two samples of A and B contain same number of molecules. If the pressure of gas B is 2atm then what will be the pressure of gas A ( atm) . If two samplest are taken in separate containers of equal volume ?
A. 16
B. 32
C. 48
D. 64

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Given m_(A)=2m
:." "mol. wt.  of A=2xxmol." " wt." " of B" "….(i)
Given" "U_(rms) of A=2xxu_(rms) of B " " ….(ii)
Also number of molecules of A = number of molecules of B" "…..(iii)
For gas A" "P_(A)V_(A)=(1)/(3)M_(A)u_(rmsA)^(2)
For gas B" "P_(B)V_(B)=(1)/(3)M_(B)u_(rmsB)^(2)
:. " "(P_(A)V_(A))/(P_(B)V_(B))=(M_(A))/(M_(B))xx(u_(A)^(2))/(u_(B)^(2))" "....(iv)
Given " "V_(A)=V_(B)" "....(v)
:." " By equation (i),(ii),(iv) and (v)
(P_(A))/(P_(B))=2xx(2)^(2)=8
:." "P_(A)=8P_(B)
Ans. 16