Help please :)

Jun 2019
Hi There,

Even though I did Chem 11 and got a good grade, I have to redo it as it has been over 10 years. I have some questions I am stuck on, and/or I am not sure if my answer is correct, I would like to double check before handing in this assignment.

9. If 3.75 x 10^24 atoms of hydrogen are found in a sample of ammonium chloride, what mass of ammonium chloride is present? NH4Cl molar mass - 53.50 g/mol

10. d.) How many molecules in 1.56 x 10^3 of methane gas at STP?

11. What volume at STP would....

a.) 6.85 x 10^22 molecules of sulphur dioxide take up.

b.) 68.7 g of helium take up.

c.) 1.78 mol of mercury gas take up.

d.) 7.51 x 10^25 molecules of nitrogen gas take up.

a.) How much would 3.42 x 10^3 L of oxygen held at STP weigh?

b.) How many atoms of oxygen would be found in the above quantity of gas.

13. How much mass and volume (at STP) of gaseous tetraphosphorus hexaoxide would be present in 9.63 x 10^24 atoms of oxygen were found in the sample?

15. If the mass of lithium atom is 6.94 amu, and that of a uranium atom is 238.1 amu, calculate the mass of the lithium atom relative to that of the uranium atom.

May 2015
New Delhi -India
Show your attempts in doing above problems.