If 4 litres of water is evaporated on bolling from 12 litres of salt solution containing 7 percentage salt, the percentage of salt in the remaining solution is

Options

A. 0.105
B. 0.115
C. 0.12
D. 0.13

Answer

To solve the problem step by step, we will follow these calculations:

### Step 1: Calculate the amount of salt in the original solution.
The original solution is 12 liters with a salt concentration of 7%.

\[ \text{Amount of salt} = \text{Total volume} \times \text{Percentage of salt} \]
\[ \text{Amount of salt} = 12 \, \text{liters} \times \frac{7}{100} = 0.84 \, \text{liters} \]

### Step 2: Calculate the amount of water in the original solution.
Since the solution is 7% salt, the remaining percentage is water.

\[ \text{Percentage of water} = 100\% - 7\% = 93\% \]
\[ \text{Amount of water} = 12 \, \text{liters} \times \frac{93}{100} = 11.16 \, \text{liters} \]

### Step 3: Calculate the amount of water remaining after evaporation.
4 liters of water is evaporated from the original solution.

\[ \text{Remaining water} = \text{Original water} - \text{Evaporated water} \]
\[ \text{Remaining water} = 11.16 \, \text{liters} - 4 \, \text{liters} = 7.16 \, \text{liters} \]

### Step 4: Calculate the total volume of the remaining solution.
After evaporation, the total volume of the remaining solution is the sum of the remaining salt and water.

\[ \text{Total remaining solution} = \text{Remaining salt} + \text{Remaining water} \]
\[ \text{Total remaining solution} = 0.84 \, \text{liters} + 7.16 \, \text{liters} = 8 \, \text{liters} \]

### Step 5: Calculate the percentage of salt in the remaining solution.
To find the percentage of salt in the remaining solution, we use the formula:

\[ \text{Percentage of salt} = \left(\frac{\text{Amount of salt}}{\text{Total remaining solution}}\right) \times 100 \]
\[ \text{Percentage of salt} = \left(\frac{0.84 \, \text{liters}}{8 \, \text{liters}}\right) \times 100 = 10.5\% \]

### Final Answer:
The percentage of salt in the remaining solution is **10.5%**.

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