Entropy help?

Question

What is the sign of the entropy change in each chemical reaction?

a) N2O4(g) → 2 NO2(g)

b) PCl3(g) + Cl2(g) → PCl5(g)

c) 2 Al(s) + 3/2 O2(g) → Al2O3(s)

d) N2(g) + 3 H2(g) → 2 NH3(g)

e) S(s) + O2(g)→ SO2(g)

Please help =(

You don't have to answer all of them, just please explain how you can tell entropy affects a reaction.

Thank you!

Answer 1

a) positive more molecules so more states

b) negative less molecules

c) negative a gas having a great entropy removed

d) negative as b

e) = since same number of gas mole and entropy of solid very low