Answer:
copper(ll) carbonate
Step-by-step explanation:
Since the product is a salt which is copper(II) carbonate, water and carbon dioxide, this reaction is an acid + metal carbonate reaction.
Looking at the salt, Cu²⁺ has to be part of the reactants.
Hence, the missing compound there has to be copper(ll) carbonate, CuCO₃.
The balanced chemical equation would be:
CuCO₃ + 2HNO₃➙ Cu(NO₃)₂ +H₂O +CO₂
P.s. You left out CO₂ as a product in Q2 ;)
Just a recap of the main reactions you would've learnt:
1) Acid + base/ alkali ➙ salt + water
2) Acid + metal ➙ salt + hydrogen gas
3) Acid + metal carbonate ➙ salt + H₂O + CO₂