Correct option is A
The correct answer is (a) EBT
Explanation:
- EBT stands for Eriochrome Black T, a complexometric indicator.
- It is used in the EDTA titration method to determine the total hardness of water.
- Hardness is caused by the presence of Calcium ($Ca^{2+}$) and Magnesium ($Mg^{2+}$) ions.
- EBT forms a wine-red complex with these metal ions.
- As EDTA is added, it displaces EBT, and at the endpoint, the solution turns from wine-red to steel blue.
Information Booster:
- The titration is usually performed at a pH of 10 using an ammonia buffer.
- Water hardness is typically expressed in terms of $CaCO_3$ equivalents.
Additional Knowledge:
Phenolphthalein (Option b)
- Used for acid-base titrations; turns pink in basic solutions.
Methyl orange (Option c)
- Used for acid-base titrations; turns red in acidic and yellow in basic solutions.
So the correct answer is (a)
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