Answer:
3 Cu + 8 HNO3 --> 3 Cu(NO3)2 + 2 NO + 4 H2O
Explanation:
Make sure both sides are equal
3 <u>Cu</u> + 8 H<u>N</u>O3 --> 3 <u>Cu</u>(NO3)2 + 2 <u>N</u>O + 4 H2O
// start by those elements that change their oxidation degree
<u>Cu</u> and <u>N</u>
// also you can write reduction-oxidation reactions
+ 2
-->
| 2
- 3
-->
| 3
// write the numbers of electrons that are lost/gained as the coefficients of the opposite elements
// then check if H and O are the same on both sides
// adjust if they aren't.