Answer: The molar mass of the gas is 9.878 g/mol.
Explanation:
According to Graham's law, the rate of diffusion is inversely proportional to square root of molar mass of gas.

where,
M = molar mass of gas
As given gas diffuses 1/7 times faster than hydrogen gas. So, its molar mass is calculated as follows.

where,
= molar mass of hydrogen gas
= molar mass of another given gas
= rate of diffusion of hydrogen
= rate of diffusion of another given gas = 
Substitute the values into above formula as follows.

Thus, we can conclude that the molar mass of the gas is 9.878 g/mol.
1 mole ----------- 6.02x10²³ molecules
? moles --------- 1.9x10²⁵ molecules
moles = 1.9 x 10²⁵ * 1 / 6.02x10²³
= 1.9 x 10²⁵ / 6.02x10²³
= 31.561 moles
hope this helps!
Answer:
A.It lowers the melting point of alumina. B.It increases the electrical conductivity. ... Hint: The solution of alumina and cryolite during the electrolysis gives the aluminium at cathode and oxygen at anode. The alumina is a poor conductor of electricity and the fusion temperature of alumina is about 2000∘C.
I believe what you are trying to ask here is the balanced chemical reaction. We first identify the chemical formula of the substances.
Lead(II) sulfide = PbS
Oxygen = O2
Lead(II) oxide = PbO
Sulfur dioxide = SO2
The balanced chemical reaction is written as:
PbS + 3/2O2 = PbO + SO2