Question

Q21. Residual hardness left in hot Lime-Soda
process is about
(A) 50-60 ppm
(B) 2-3 ppm
(C) 15-30 ppm
(D) 80-90 ppm​

Answer 1

Answer:

● Residual hardness left in hot Lime-Soda process is about 15-30 ppm.

Answer 2

Answer: The correct option is (C)

The residual hardness left in hot Lime Soda is 15-30 ppm

Explanation:

• Hard water's hardness can be removed by putting the water to boil. This consequently helps soften the water containing carbonates.
• Residual hardness is one such type of hardness in water due to noncarbonates and can be termed as permanent hardness of water.
• Sodium carbonate, filtration through zeolites and lime are some ways to remove it.

Hence, the correct option is (C). The residual hardness left in hot Lime Soda is 15-30 ppm.