What is the answer to b? What is the chemical equation for this reaction?

Answer:
blue copper(ii) nitrate - Cu(NO3)2
nitrogen dioxide - NO2
Oxygen - O (usually O2)
Copper(ii) Oxide - CuO
(Btw, this is a decomposition reaction)
so we get the equation
Word: Copper(ii) nitrate ⇄ Nitogen dioxide + Copper(ii)Oxide+Oxygen
Chemical: Cu(NO3)2 ⇄ NO2 + O2+ CuO
now when we balance the equation, it becomes...
2Cu(NO3)2⇄ 4NO2 + 2CuO+ O2