If the number of moles of a gas initially contained in a 2.10 l vessel is doubled, what is the final volume of the gas in liters? (assume the pressure and temperature remain constant.) none of the above 8.40 4.20 1.05 6.30

Avagadro's law gives the relationship between volume and number of moles of gas. 
At constant temperature and pressure , volume of gas is directly proportional to number of moles of gas. 
V / n = k
where V - volume, n - number of moles , k - constant 

parameters for the first instance are on the left side and parameters for the second instance are on the right side of the equation 

initial number of moles - N
after doubling - 2N
initial volume - 2.10 L
final volume - V
substituting in the equation 


V = 4.20 L
new volume is 4.20 L

The answer is neonhope it

Reaction type : double replacement hcl + lioh = h2o + licl