Contracting and expanding gases

Question

Assignment:

Q1. A sample of N₂ gas occupies 2.40 L at 20^oC. If the gas is in a container that can contract or expand at constant pressure, at what temperature will the N₂ occupy 4.80 L?

10^oC
40^oC
146^oC
313^oC
685^oC

Q2. When 0.56 g of Na(s) reacts with excess F2(g) to form NaF(s), 13.8 kJ of heat is evolved at standard-state conditions. What is the standard enthalpy of formation (ΔH) of NaF(s)?

+24.8 kJ/mol
+570 kJ/mol
-24.8 kJ/mol
-7.8 kJ/mol
-570 kJ/mol

Q3. Given:

H₂(g) + ½O₂(g) H₂O(l), ΔH = -286 kJ

What is the enthalpy change for the following reaction?

2H₂O(l) 2H₂(g) + O₂(g), ΔH^o_rxn = ?

ΔH^o = -286 kJ
ΔH^o = +286 kJ
ΔH^o = -572 kJ
ΔH^o = +572 kJ
ΔH^o = -143 kJ