Answer:
1) All the options are true, large masses of water help to regulate the temperature, control temperature fluctuations and reduce the atmospheric CO2-
2) The "common" water is made of H2O, this means that it is made of hydrogen and oxygen, so the right answer is the fourth option.
3) Salinity is expressed in (gr of salt)/(kg of water), so is expressed in parts per 1000, it refers to the amount of dissolved salt in water (not any particle, and not only in seawater, so the option 2 is wrong)
and is represented by the sign %, which means percent.
So the only correct option is the first one.
4) True, it's around 333 million cubic miles of water.
