How many moles are in 4.2 g of H2O

The continuous release of nuclear energy caused when one fission reaction triggered more nuclear reactions is a

If i initially have a gas at a pressure of 12 atm, a volume of 23 liters, and a temperature of 200 k, and then i raise the pressure to 14 atm and increase the temperature to 300 k, what is the new volume of the gas?

What is a possible quantum number set for an electron in the 3s orbital of a magnesium atom