Write the structures of the main products when `CH_(3)CH_(2)CHO` reacts with the following reagent :
(i) `Zn-Hg//"Conc".HCl`

Explanation

To solve the problem of determining the main product when propanal (CH₃CH₂CHO) reacts with Zn-Hg in the presence of concentrated HCl, we can follow these steps:

### Step 1: Identify the Reactant
The reactant given is propanal, which has the structure:
```
O
||
CH₃-CH₂-C-H
...