A glass tube of volume 112ml,containing a gas is partially evacuated till the pressure in it drops to 3.8*10^-5 torr at 0⁰C.the number of molecules of the gas remaining in the tube is?

volume = 0.112 L

pressure = 3.75 atm

temp = 273K

gas law is PV=nRT

n=3.75*0.112/(0.0821*273)

n=0.01874 moles

A mole has 6.0221415×10²³ atoms or molecules of the pure substance being measured

no. of molecules = 112.87x10²⁰

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regards

Ramesh

HI sameer ali

V=112 ml

P = 3.8*10^-5 torr

T=0⁰C=273 k

Use the formula PV=nRT

here n number of mole

and R is gas constant

and find the value of n

and we know that 1 mole of gas contain 1 avagadro number(A) of molecules

so n mole of contain n*A number of molecule at 0⁰C

Take care of units during calculation