3.47 L of a gas at 302 K and a pressure of 740 mmHg was found to have a mass of 5.16 g. Calculate the molar mass.

The answer for #3 is c but i don't know why

Harvey kept a balloon with a volume of 348 milliliters at 25.0˚c inside a freezer for a night.  when he took it out, its new volume was 322 milliliters, but its pressure was the same.  if the final temperature of the balloon is the same as the freezer’s, what is the temperature of the freezer? the temperature of the freezer is  kelvins.

Draw two cyclic constitutional isomers of cis-1