Assertion :Soft water lathers with soap but not hard water Reason: Hard water reacts with soap t form insoluble salts which form scum, not lather

Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

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Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

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Assertion is correct but Reason is incorrect

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Both Assertion and Reason are incorrect

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Solution

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
Hard water contains calcium and magnesium salts which react with soap containing sodium stearate $(C_{17} H_{35} C O O N a)$ to precipitate out Ca/Mg stearate.
$2 R C O O N a + C a^{2 +} \to (R C O O)_{2} C a + 2 N a^{+}$
$2 R C O O N a + M g^{2 +} \to (R C O O)_{2} M g + 2 N a^{+}$

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