A student mixes quick lime and water in a test tube and touches its side surface. Which of the following statement correctly describes the student's observation?

The test tube becomes cold due to release of heat energy.

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The test tube becomes hot due to release of heat energy.

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The test tube becomes hot due to absorption of heat energy.

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The test tube becomes cold due to absorption of heat energy.

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Solution

The correct option is B
The test tube becomes hot due to release of heat energy.

When quick lime (calcium oxide) is mixed with water, a combination reaction takes place and calcium hydroxide is formed, which is an exothermic reaction, i.e., the reaction is accompanied by release of energy. So, the test tube becomes hot due to release of heat energy.

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