A gas mixture contains `50%` helium and `50%` methane by volume. What is the percent by weight of methane in the mixture.

A gaseous mixture contain 50% He and 50% CH_4 by volume. What is the percent by weight of CH_4 in the mixture ?

A gas mixture contains 25% He and 75% CH_(4) by volume at a given temperature and pressure. The percentage by mass of methane in the mixture is approximately _________ .

A mixture of 20% ethanol and 50% gasoline is called as.

The diameter of cross-section of a wire is reduced by 50%. If the volume remains constant, what percent of length of the wire should be increased?