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Which of the given statements about hard water is/are correct: 1. Contains sulfates, chlorides, bicarbonates of calcium and magnesium. 2. Hard water forms lather with both soap and detergent.

Which of the given statements about hard water is/are correct: 1. Contains sulfates, chlorides, bicarbonates of calcium and magnesium. 2. Hard water forms lather with both soap and detergent. Correct Answer Only 1

The correct answer is Only 1 

CONCEPT:

  • Hard water is water that contains calcium and magnesium salts in the form of bicarbonates, chlorides and sulfates.


EXPLANATION:

  • Hard water does not form lather with soap.
  • It forms scum/precipitate with soap.
  • Sodium stearate in soap reacts with calcium/magnesium and forms calcium stearate or magnesium stearate.
  • Ca2+ + RCOONa → RCOOCa + 2Na+
  • Mg2+ + RCOOna → RCOOMg + 2Na+
  • When all the Ca2+ and Mg2+ ions present in hard water precipitated the resulting water becomes soft. So it is not suitable for washing as a lot of soap get wasted.
  • Detergents are ammonium or sulphonate salts of long-chain carboxylic acids.  The charged end of these compounds does not form any insoluble precipitates. Thus they remain effective in hard water.

Hint

  • Statement is about the hardness of water. It is of two type-
  • Temporary hardness is caused by the presence of dissolved bicarbonates of Calcium (Ca(HCO3)2 ), Magnesium (Mg(HCO3)2 ), Iron and other heavy elements.
  • Permanent Hardness is due to the presence of dissolved chlorides and sulphates of Calcium, Magnesium, Iron and other heavy elements.

Related Questions

Which of the following are characteristics/properties of permanent hardness in water? (A) Presence of bicarbonates of calcium and magnesium (B) Presence of sulphates of calcium and magnesium (C) Forms good lather when comes in contact with soap (D) Presence of chloride of calcium and magnesium (E) Can be removed by boiling the water Choose the correct answer from the options given below :
There are two types of detergents – P and Q. Detergent P contains 60% soap and 40% bleach, while Detergent Q contain 82% soap and 18% of bleach. In what ratio should the detergents P and Q be mixed, so that the resultant mixture contains 72% of soap in it?
Read the given statements carefully and answer the questions. Statement: Sunil has only Rs 100. He has to buy a soap, an oil bottle, a kilo of potatoes and a chocolate. Which of the following combinations would Sunil buy? A. An oil bottle of Rs 44, chocolate of Rs 23, soap of Rs 2 and half kg of potatoes of Rs 16. B. An oil bottle of Rs 40, chocolate of Rs 20, soap of Rs 17 and a kg of potatoes for Rs 34. C. Half a kilo potato of Rs 12, soap of Rs 23, chocolate of Rs 5 and an oil bottle of Rs 39. D. Chocolate of Rs 50, soap of Rs 7, an oil bottle of Rs 30 and a kg  of potato of Rs 29 per kg.
An alloy of zinc, magnesium, and copper contains 80% of copper, 15% of zinc, and 5% of magnesium. The second alloy of copper and magnesium only is melted with the first and the mixture contains 75% of copper, 5% of zinc and 20% of magnesium. What is the percentage of magnesium in the second alloy?
Read the instructions below and answer the questions that follow: P * Q means “some P are Q”. P – Q means “all P are Q”. P + Q means “no P is Q”. Now, statements below are followed by two conclusions. You have to take the given statements to be true even if they seem to be at variance from commonly known facts. Read all the conclusions and then decide which of the given conclusions logically follows from the given statements disregarding commonly known facts. Statements: Ant * hall Hall * soap Soap + dog Dog * doll Conclusions: I. Ant * soap II. Soap + doll
Assertion (A) : Synthetic detergents can lather when in hard water.Reason (R) : Synthetic detergents form soluble calcium and magnesium salts with hard water.
Assertion (A) : Synthetic detergents can lather when in hard water.
Reason (R) : Synthetic detergents form soluble calcium and magnesium salts with hard water.
Assertion (A) Synthetic detergents can lather well in hard water.
Reason (R) Synthetic detergents form soluble calcium and magnesium salts with hard water.
Consider the following statements
1. The soap available in the market use various ingredients in their preparation like colour perfume and oils.
2. Broadly, soaps can be divided into hard soap and soft soap categories.
Which of the statement(s) given above is/are correct?
Which of the following statement(s) is/are correct?
1. If sodium carbonate and washing soda is mixed in water the hardness of water can be removed.
2. The reaction of the chemicals produce sodium sulphate, sodium carbonate and insoluble calcium carbonate.
3. Magnesium sulphate chloride and magnesium carbonate is also produced.
Select the correct answer