1)A sample of CO2 gas which weighs 0.85 grams has a volume of 1.30 liters when collected at 30°C. What would be the pressure of the gas sample?

Question

2) A gas sample has an original volume of 600 ml when collected at 720 mm and 35°C. If a change is made in the gas temperature which causes the volume of the gas sample to become 520 ml at 1.00 atm, what is the new temperature?
3) A gas sample has an original volume of 760 ml when collected at 720 mm and 25°C. What will be the volume of the gas sample if the pressure increases to 820 mm and the temperature increases to 40°C?
4)H3AsO4 + Zn + HNO3 → AsH3 + Zn(NO3)2 + H2O

Answer 1

a. PV = nRT and n = grams/molar mass
b. (V1/T1) = (V2/T2)
3. (P1V1/T1) = (P2V2/T2)
4. This is a redox equation. This link will tell all about how to do these.
http://www.chemteam.info/Redox/Redox.html