i need the formula nd solution

1. How many molecules of O2 will react with 6.022 1023 molecules of H2 to make water? The reaction is 2H2(g) + O2(g) 2H2O().

2. How many molecules of H2 will react with 6.022 1023 molecules of N2 to make ammonia? The reaction is N2(g) + 3H2(g) 2NH3(g).

3. How many moles are present in 6.411 kg of CO2? How many molecules is this?

4. How many moles are present in 2.998 mg of SCl4? How many molecules is this?

5. What is the mass in milligrams of 7.22 1020 molecules of CO2?

6. What is the mass in kilograms of 3.408 1025 molecules of SiS2