Question

Use the mole ratio of CuO produced per mole of malachite to write a balanced equation for the malachite decomposition reaction. Assume that CO2 is also a product of the decomposition.

Answer 1

Here is a site that gives the formula for malachite, CuCO3.Cu(OH)2.

So I would write the decomposition reaction as
CuCO3.Cu(OH)2 ==> 2CuO + CO2 + H2O
Looks balanced to me and follows the directions.