100gm of an aq. solution of sugar contains 40% sugar by mass. How much water should be evaporated get 50% sugar solution by mass?

Options

A. 10g
B. 20g
C. 0.10g
D. 0.20g

Explanation

To solve the problem, we need to determine how much water should be evaporated from a 100 g sugar solution that initially contains 40% sugar by mass in order to achieve a final solution that contains 50% sugar by mass.

### Step-by-Step Solution:

1. **Determine the initial mass of sugar and water:**
- The solution is 100 g and contains 40% sugar by mass.
- Mass of sugar = 40% of 100 g = 40 g.
- Mass of water = Total mass - Mass of sugar = 100 g - 40 g = 60 g.

2. **Determine the final conditions:**
- We want a final solution that is 50% sugar by mass.
- In a 100 g solution at 50% sugar, the mass of sugar would be 50 g.
- Therefore, the mass of water in the final solution must also be 50 g (since 50% sugar means 50% water).

3. **Calculate the amount of water to be evaporated:**
- Initial mass of water = 60 g.
- Final mass of water needed = 50 g.
- Amount of water to be evaporated = Initial mass of water - Final mass of water = 60 g - 50 g = 10 g.

4. **Conclusion:**
- To achieve a 50% sugar solution, 10 g of water should be evaporated.

### Final Answer:
10 g of water should be evaporated.

---