Control and Coordination — Science STD 10 — Question

In an ecosystem :

1. The flow of energy is unidirectional.
2. The flow of materials is unidirectional.
3. The flow of materials is cyclic.
4. The flow of energy is cyclic.

Which of the following method of contraception protects a person from acquiring a sexually transmitted disease?

Which of the following metal exists in the liquid state?

Common salt besides being used in kitchen can also be used as the raw material for making:

1. Washing soda.
2. Bleaching powder.
3. Baking soda.
4. Slaked lime.

Upto which element, the Law of Octaves was found to be applicable:

A student puts a drop of reaction mixture of a personification reaction first on a blue litmus paper and then on a red litmus paper. He may observe that:

Which of the following changes occur when you walk out of bright sunshine into a poorly lit room?

Sodium hydroxide is used :

Quicklime when dissolved in water gives :