The answer to this question is A
Answer:
Hydrogen, H_2
Explanation:
mass of each gas is 10.0 g
number of mole = mass/ molar mass
number of moles is directly proportional to volume at constant temp and pressure
this implies that the volume is inversely proportional to molar mass. And Among all the gases in periodic table the molar mass of Hydrogen is the least.
molar mass of H2=2 g/mol
Since, H2 has minimum molar mass then for the same mass of the gases Hydrogen will have maximum volume.
Answer: number of atoms is 5.21 · 10^24
Explanation: Atomic mass of Be is 9.012 g/mol.
Number of moles n = m/M = 78.0 g / 9.012 g/mol =
Multiply this with Avogadro number Na = 6.022*10^23 1/mol
C. Also just look up a chemical equation balancer calculator next time.