Explore Exams
Test Series
Live Tests
Prev. Papers
Quizzes
Live Quizzes
Current Affairs
News
Prepp+
GamesLogin / Register
All Exams Test series for 1 year @ ₹349 only
Question
CDS - 2018
General Science

Which of the following substances cause temporary hardness in water?

1. Mg(HCO 3) 2

2. Ca(HCO 3) 2

3. CaCl 2

4. MgSO 4

Select the correct answer using the code given below.

This question was previously asked in
CDS I 2018 Elementary Mathematics Previous Year Paper (04-Feb-2018)
Attempt Now
The correct answer is

1 and 2

  • Temporary hardness in water is caused by Mg(HCO3)2 (Magnesium hydrogen carbonate) and Ca(HCO3)2 (Calcium bicarbonate).
  • Hard water is water that contains +2 cations, especially Ca2+ and Mg2+. Therefore, both of the aforementioned "salts" impart hardness to water. Water hardness can be removed by boiling water, the ion-exchange process, Calgon's process, adding washing soda, etc.
Was this answer helpful?

Similar Questions

  1. ‘German silver’ is used to make decorative articles, coinage metal, ornaments, etc. The name is given because:

    CDS - 2016
    General Science
    View Answer

  2. Which among the following methods is used to separate the constituents present in compound?

    CDS - 2023
    General Science
    View Answer

  3. Which one of the following statements regarding acids is not correct?

    CDS - 2023
    General Science
    View Answer

  4. School bells are made of metals because metals are

    CDS - 2022
    General Science
    View Answer

  5. Which one of the following is used in soda-acid fire extinguishers?

    CDS - 2021
    General Science
    View Answer

  6. Bright light is found to emit from photographer’s flashgun. This brightness is due to the presence of which one of the following noble gases?

    CDS - 2018
    General Science
    View Answer

Important Questions from Chemistry in Everyday Life

  1. The plastics which get deformed easily on heating are known as:

    General Science
    View Answer

  2. CNG stands for which among the following?

    General Science
    View Answer

  3. Milk becomes sour if kept outside the refrigerator in summer because of:

    General Science
    View Answer

  4. Which of the following is a ferrous mineral?

    General Science
    View Answer

  5. Which among the following methods do most Indian households use for obtaining safe drinking water?

    General Science
    View Answer
Need Expert Advice?
Upcoming Exams
NDA
September 13, 2026
CDS
September 13, 2026
Test Series
CDS img
Defence
UPSC CDS 2026 Mock Test Series
540 Tests 4 Tests Free
1126 Attempts
4.3(168)
English, Hindi
View Test Series
More Questions from CDS
1)

In the following items Match List I with List II and select the answer using the code given below the Lists :
 

List I (Word/Expression/Specialised term)List II (Meaning)
A. Incensed1. Designed to cause fires
B. Incendiary2. Unmindful of potential risks
C. Incautious3. Giving out light when heated
D. Incandescent4. Enraged

Code :
A B C D

2)

In the following items Match List I with List II and select the answer using the code given below the Lists :
 

List I (Word/Expression/Specialised term)List II (Meaning)
A. Bequeath1. To pledge property as a security
B. Mortgage2. To leave property for beneficiary via a will
C. Endowment3. Agreement for use of property against rent
D. Lease4. To grant funds for running a socially-beneficial institution

Code :
A B C D

3)

In the following items Match List I with List II and select the answer using the code given below the Lists :

List I (Word/Expression/Specialised term)List II (Meaning)
A. Ascribe1. Associate ownership or authorship with
B. Prescribe2. Carve, cut or etch into a material or surface
C. Proscribe3. Lay down a rule
D. Inscribe4. Officially forbid

Code :
A B C D

4)

In the following items Match List I with List II and select the answer using the code given below the Lists :
 

List I (Word/Expression/Specialised term)List II (Meaning)
A. Implication1. The act of communicating with / praying to a deity
B. Complication2. A verbal or written request for an official purpose
C. Supplication3. A meaning not clearly stated but which can be inferred
D. Application4. A situation or condition that is complex or confused

Code :
A B C D

5)

In the following items Match List I with List II and select the answer using the code given below the Lists :
 

List I (Word/Expression/Specialised term)List II (Meaning)
A. Blizzard1. Tropical cyclones over the western Pacific Ocean
B. Tornado2. A storm with thunder and lightning, and usually heavy rain
C. Thunderstorm3. Severe snowstorm with strong winds
D. Typhoons4. A violently rotating destructive column of air that extends from a thunderstorm to the ground

Code :
A B C D

6)

Either my brothers  / or my friend  / are coming to receive me at the airport.  / No error. 
            (a)                          (b)                                        (c)                                          (d)

7)

In the following items Match List I with List II and select the answer using the code given below the Lists :
 

List I (Word/Expression/Specialised term)List II (Meaning)
A. Pragmatist1. Using too many words
B. Promethean2. Daringly original and creative
C. Promontory3. A headland that juts into a large water body
D. Prolix4. A person concerned with practical matters

Code :
A B C D

8)

In the following items Match List I with List II and select the answer using the code given below the Lists :
 

List I (Word/Expression/Specialised term)List II (Meaning)
A. Epitaph1. Words written about a dead person
B. Epistle2. An adjective to describe character or characteristic
C. Epithet3. A short phrase expressing an idea in a clever way
D. Epigram4. A formal letter

Code :
A B C D

9)
The passage draws attention to which one among the following ?
10)
The "biophilia hypothesis" :

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App