Helium is used to fill a balloon of diameter 31 cm at 23C and 1.5 atm. The mass of a helium atom is 4.0026 u, the conversion factor from u to kg is 1.66 × 10?27 kg/u, the conversion factor from atm to Pa is 1.013 × 105 Pa/atm, the universal gas constant 8.31451 J/Kmol, the Boltzmann's constant is 1.38066 × 10?23 J/K, and Avo- gadro's number is
a. How many Helium atoms are there in the balloon?
b. What is the average kinetic energy of each Helium atom?
c. What is the average speed (i.e., the root mean square speed) of each Helium atom?