Paper is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets.

Correct Option: A

Paper is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets.

Acid rain is caused by emissions of sulfur dioxide and nitrogen oxides, which react with the water molecules in the atmosphere to produce acids.

Correct Option: B

Acid rain is caused by emissions of sulfur dioxide and nitrogen oxides, which react with the water molecules in the atmosphere to produce acids.

A mixture of water and alcohol is separated by the process of distillation. At 780C, alcohol starts to vaporize. The vapours are condensed in the condenser and alcohol is collected in the receiver.

Correct Option: D

A mixture of water and alcohol is separated by the process of distillation. At 780C, alcohol starts to vaporize. The vapours are condensed in the condenser and alcohol is collected in the receiver.

In photography, silver bromide is used on photographic film, because it is unusually sensitive to light exposure.

Correct Option: A

In photography, silver bromide is used on photographic film, because it is unusually sensitive to light exposure.

Tritium is a radioactive isotope of hydrogen. It is the lightest radioactive element.

Correct Option: C

Tritium is a radioactive isotope of hydrogen. It is the lightest radioactive element.