Engineering Questions with Answers - Multiple Choice Questions

Applied Chemistry MCQ – Estimation of Hardness – 2

1 - Question

Estimation of hardness can be determined by ________ types.
a) 2
b) 3
c) 4
d) 5

View Answer

Answer: a
Explanation: Estimation of hardness can be determined by two types. They are Soap titration method and EDTA method.




2 - Question

Total hardness of water can be determined by titrating the fixed volume of water against the standard ___________ solution.
a) Soap
b) Alkaline soap
c) Acidic soap
d) Alcoholic soap

View Answer

Answer: d
Explanation: Total hardness of water can be determined by titrating the fixed volume of water against the standard alcoholic soap solution.




3 - Question

The end point of the titration in the soap titration method is ___________
a) Formation of lather
b) Formation of salts
c) Formation of carbonates
d) Formation of bicarbonates

View Answer

Answer: a
Explanation: The end point of the titration in the soap titration method is at the formation of lather that stands for about two minutes.




4 - Question

The sodium soap will precipitate all the hardness causing ions into their respective __________
a) Carbonates
b) Bicarbonates
c) Stereates
d) Chlorides

View Answer

Answer: c
Explanation: The sodium soap will precipitate all the hardness causing ions into their respective stereates in the beginning of the soap titration method.




5 - Question

The water which form lather directly with the soap is called __________
a) Hard water
b) Soft water
c) Partially hard water
d) Very hard water

View Answer

Answer: b
Explanation: The water which forms lather directly with the soap is called soft water. The water which forms precipitates when reacted with soap is called as the hard water.




6 - Question

EDTA method is also called as _________
a) Complexometric titration
b) Complex titration
c) Complement titration
d) Complexion titration

View Answer

Answer: a
Explanation: EDTA method is also called as the complexometric titration. In EDTA method is ethylene diamine tetra acetate is the compound used to remove the hardness.




7 - Question

The indicator used in the EDTA method is ___________
a) Benzene
b) Phenopthalene
c) Ethylene diamine
d) Erichrome black T

View Answer

Answer: d
Explanation: The indicator used in the EDTA method is erichrome black T. The hardness causing ions like Ca++ and Mg++ forms the unstable complexes with reacting the erichrome black T.




8 - Question

EDTA has the ability to form _________ with metal ions.
a) Stable complexes
b) Unstable complexes
c) Salts
d) Acids

View Answer

Answer: a
Explanation: EDTA has more affinity to form stable complexes by reacting with metal ions. The EDTA forms the stable EDTA complexes.




9 - Question

The colour of dye metal complex and dye are ___________
a) Same
b) Different
c) Same in only some cases
d) Cannot be known

View Answer

Answer: b
Explanation: The colour of dye metal complex and dye are different. EDTA extracts the metal ions from the metal ion dye to form stable complex.




10 - Question

The change in colour is sharper at the PH of ________
a) 5
b) 10
c) 15
d) 20

View Answer

Answer: b
Explanation: The change in the colour of the ions is sharper at the PH of the 10 than that of the other ranges of the PH.




11 - Question

At PH=10, the metal dye complex has the colour ________
a) Wine red
b) Blue
c) Green
d) Pink

View Answer

Answer: a
Explanation: At the PH=10, the metal dye complex ion has the colour is wine red but the dye itself has the blue colour at the PH of 10.




12 - Question

To prepare EDTA solution _________ grams of EDTA is dissolved in the one litre of water.
a) 1
b) 2
c) 3
d) 4

View Answer

Answer: d
Explanation: To prepare EDTA solution, four grams of the EDTA is dissolved in the one litre of the water. This is the standard EDTA solution used to determine the hardness of water.




13 - Question

_________ drops of indicator is used in the EDTA method.
a) 1 to 2 drops
b) 2 to 3 drops
c) 2 to 4 drops
d) 5 to 8 drops

View Answer

Answer: a
Explanation: 1 to 2 drops of the indicator is used in the EDTA method. 0.5gms of the dye is dissolved into the 100ml of alcohol and the indicator of two to three drops is added.




14 - Question

The buffer used in the EDTA solution must have the PH of ___________
a) 20
b) 15
c) 10
d) 5

View Answer

Answer: c
Explanation: The buffer used in the EDTA solution must have the PH of 10. Freshly prepared solutions are more affective to have the accurate results.




15 - Question

The standard hard water is prepared such that each ml must contain ________ mg of CaCO3.
a) 1
b) 2
c) 3
d) 4

View Answer

Answer: a
Explanation: The 1g of pure CaCO3 is dissolved in the minimum amount of concentrated HCL diluted to 1ltr of distilled water such that it contains 1mg of CaCO3.

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