The tabulated results below were obtained by titration 10.0 cm3 of water with soup. The titration was repeated with the same sample of water after boiling. The ratio of permanent to temporary hardness is
1.5
1.4
4.1
5.1
Explanation
Video Explanation
No video available
Post your Contribution
Discussions (21)
There are two demarcations in the table: before and after boiling. Before boiling was when nothing has happened so its insignificant. Now we are to use after boiling cuz that's when we got permenant and temporary results . so according to the question, we were asked to find the ratio of permanent to temporary hardness of water. The final is the permanent hardness of water which is = 20. While the temporarily should be 20-15=5 . so we have ratio of 20:5=4:1
I don't agree with you guys and myschool. From the table it can be deduced that before boiling, there is presence of temporary and permanent hardness. Then, after boiling, we are only left with permanent hardness. It call be calculated as follows:
Temp + perm hardness used up 25cm³ of soap
Perm hardness used up 20-15 = 5cm³
Therefore, Temp hardness will use up 25-5 = 20cm³
ratio of permanent to temporary hardness = 5:20
which is = 1:4 
B is the answer
Degree of hardness varies directly as the amount of soap used
Before boiling, hardness is temporary + permanent = 25 - 0 = 25
After boiling, hardness is only permanent has boiling eliminates temporary hardness = 20 - 15 = 5
Temporary hardness = 25 - 5 = 20
Ratio of permanent to temporary = 5:20 = 1:4
OPTION B
OPTION B
To determine the ratio of **permanent to temporary hardness**, we first understand the given data:
-
**Before boiling**:
- Initial volume = **0.0 cm³**
- Final volume = **25.0 cm³**
- Soap solution used = **25.0 - 0.0 = 25.0 cm³**
-
**After boiling**:
- Initial volume = **15.0 cm³**
- Final volume = **20.0 cm³**
- Soap solution used = **20.0 - 15.0 = 5.0 cm³**
### Step 1: Understanding Hardness
- **Total hardness** = Soap solution used **before boiling** = **25.0 cm³**
- **Permanent hardness** = Soap solution used **after boiling** = **5.0 cm³**
- **Temporary hardness** = **Total hardness - Permanent hardness** = **25.0 - 5.0** = **20.0 cm³**
### Step 2: Calculate Ratio
` \text{Ratio} = \frac{\text{Permanent Hardness}}{\text{Temporary Hardness}} `
= \frac{5.0}{20.0} = 1:4 \Rightarrow 1.4 ]
Thus, the correct answer is: **B. 1.4**
