Question

`25mL` samples of distiled water, tap water and boiled water required, respectively, `1mL, 13mL` and `5mL` of soap solution to form a permanent lather. The ratio of temporary to permanent hardness in the tap water is
A. `3:2`
B. `2:3`
C. `1:2`
D. `2:1`

Answer 1

Correct Answer - D

Volume of soap solution used effectively in boiled
Water =`5-1=4 mL`
`:.` Temporary +Permanent hardness `=12 mL`
Permanent hardness =4 mL
Temporary hardness =8mL
`:. ("Temporary hardness ")/("Permanent hardness")=8/4=2:1`