The following reaction: H2 + I2 → 2HI, is an example of

a) synthesis.
b) decomposition.
c) single-displacement.
d) double-displacement.

The following reaction: H2 + I2 → 2HI, is an example of  synthesis reaction

Explanation:

Synthesis reaction:

In simple words, synthesis reaction can be stated as two or more material merge to form a new material.                A+X -->AX A synthesis reaction is always exothermic since they deliver power in the form of heat and light.When the metal and nonmetals are combined they produce an ionic compound.A synthesis reaction is essentially the reversal of decomposition reaction.The example of Synthesis reaction would be 2 H2(g) + O2(g) -->2 H2O(g)3 H2(g) + N2(g)--> 2 NH3(g)

The correct name for n3-ion should be azide.