A solution of ethanol in water is `10%` by volume. If the solution and pure ethanol have densities of `0.9866g//"cc"` and `0.785g//"cc"` respectively, find the per cent by weight.

Explanation

To solve the problem of finding the percentage by weight of ethanol in a solution that is 10% ethanol by volume, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Given Information**:
- Volume percentage of ethanol in the solution = 10%
- Density of the solution = 0.9866 g/cc
- Density of pure ethanol = 0.785 g/cc
...