A sample of krypton gas collected at STP occupies a volume of 15.6 L. How many moles of gas does the sample contain?

Answer 1

An important fact that you should have learned is that 1 mole of any gas at standard temperature and pressure (STP) occupies 22.4 liters. So 15.6 L would be (15.6/22.4) moles or 0.696 moles of krypton gas.