The main constituent of Vinegar is:

Which of the following statements regarding heavy water are correct?

$1$. It is extensively used as a moderator in nuclear reactors.

$2$. It cannot be used in exchange reactions to study reaction mechanisms.

$3$. Viscosity of heavy water is relatively smaller than that of ordinary water.

$4$. The dielectric constant of heavy water is smaller than that of ordinary water.

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Which of the following are some important pollutants released by steel industry in India?

1. Oxides of sulphur

2. Oxides of nitrogen

3. Carbon monoxide

4. Carbon dioxide

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Which of the following is/are the example/examples of chemical change?

1. Crystallization of sodium chloride

2. Melting of ice

3. Souring of milk