Carbon and its Compounds — Science STD 10 — Question

It is important to make small check dams across the flooded gullies because they :

1. Hold water for irrigation.
2. Hold water and prevent soil erosion.
3. Recharge ground water.
4. Hold water permanently.

Disposable plastic plates should not be used because :

Which of the following metals are extracted by the electrolysis of their molten chlorides?

A solution turns blue litmus red. Its pH is likely to be:

When a ray of light travelling in glass enters into water obliquely :

The phloem tissue in plants is responsible for the transport of:

In human males, the testes lie in the scrotum, because it helps in the:

The elements A, B, C and D belong to groups 1, 2, 14 and 17 respectively of the periodic table. Which of the following pairs of elements would produce a covalent bond?