1. Sulphur (1.256g) was reacted with flourine gas to form 5.722g SFx gas. The equation for the reaction is S + yF2 --> SFx. What is the value of x? (relative atomic mass: S=32: F=19)

2. A 2.89g sample of an oxide of osmium was found to contin 2.16g osmium. What is the emperical formula of the oxide? (Relative atomic mass : O=16, Os=190)

3 Calculate the mass of NO gas formed when 5.0g copper was completely oxidised by the nitrate ion. (relative atomic mass: N=14; O=16, Cu=64)