Question

write equilibrium constant expression for each reaction.
a) The oxidation of ammonia with CIF3 in a rocket motor NH3(g) + CIF(g)-><-3HF(g) + 1/2N2 + 1/2Cl(g)
b.) The simultaneous oxidation and reduction of a chlorite ion. 3Cl-2(aq)-><-2ClO-3(aq) + Cl-(aq)
c.) IO-3(aq) + 6OH-(aq) +Cl2(aq)-><-IO5-6(aq) +3H2O(i)

Answer 1

Equilibrium expressions are fundamental to chemistry and you need to know how to do them. I'll explain what you don't understand about the process. What are you having trouble. Basically its products over reactants with coefficients becoming exponents.
I think you need to check your post for typos. I see two or three and first glance.

Answer 2

a.) The simultaneous oxidation and reduction of a chlorite ion 3ClO-2(aq)-><-2ClO-3(aq) + Cl-(aq.
b.) IO-3(aq) + 6OH-(aq) + Cl(aq)-><-IO-5,6(aq) + 3H2O(i).