Which of the following substances cause temporary hardness in water? 1. Mg(HC03)2 2. Ca(HC03)2 3. CaCl2 4. MgS04 Select the correct answer using the code given below.

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Q: 30 (CDS-I/2018)

Which of the following substances cause temporary hardness in water?
1. Mg(HC03)2
2. Ca(HC03)2
3. CaCl2
4. MgS04
Select the correct answer using the code given below.

question_subject: 

Ecology

question_exam: 

CDS-I

stats: 

0,23,39,15,17,7,23

keywords: 

{'cacl2': [0, 0, 0, 1], 'temporary hardness': [0, 0, 0, 3], 'substances': [0, 0, 1, 1], 'water': [65, 15, 80, 129], 'mgs04': [0, 0, 0, 1]}

Temporary hardness in water is caused by the presence of dissolved bicarbonate ions (HCO3-). When these ions are present in water, they react with heat or with the addition of a strong base like lime (calcium hydroxide) to produce insoluble carbonates or hydroxides.

Let`s dissect each option to determine which substances cause temporary hardness in water:

Option 1: Mg(HCO3)2 (Magnesium bicarbonate) - This substance contains bicarbonate ions and can contribute to temporary hardness in water.

Option 2: Ca(HCO3)2 (Calcium bicarbonate) - This substance contains bicarbonate ions and can contribute to temporary hardness in water.

Option 3: CaCl2 (Calcium chloride) - This substance does not contribute to temporary hardness in water. It does not contain bicarbonate ions.

Option 4: MgSO4 (Magnesium sulfate) - This substance does not contribute to temporary hardness in water. It does not contain bicarbonate ions.

Based on our analysis, options 1 and 2 both contain substances that cause temporary hardness in water. Therefore, the correct answer is Option 4: 1 and 2.

Note: The correct answer provided in the question is indeed correct.