Real life examples of limiting reactants

Write skeleton equations for the following reactions c. aluminum(s)+copper(i) chloride(aq) > aluminum chloride(aq)+copper(s)

Liquid ammonia is produced at high temperatures and under great pressure in a tank by passing a mixture of nitrogen gas and hydrogen gas over an iron catalyst. the reaction is represented by the following equation. n2(g) + 3h2(g) → 2nh3(g) changing all but one experimental condition will affect the amount of ammonia produced. that condition is a) increasing the concentration of both reactants b) changing the temperature within the tank c) decreasing the pressure within the tank. d) increasing only the amount of nitrogen present.

The empirical formula of a compound is ch2o and its mass is 120 amu/molecule, what is its formula?