The World of Metals and Non-metals — Science STD 7 — Question

Name the salt formed when hydrochloric acid reacts with sodium hydroxide solution (a base).

Some definitions are given below which can be corrected by changing one word. Correct them: The evaporation of water from oceans and its arrival back into oceans is called vapour cycle.

For a bulb to glow, it must be connected to a battery. Why?

Which of the two carry oxygen rich blood, arteries or vein?

What are the main hazards of wool industry?

What do you mean by the transfer of heat?

Are there any substances whose odours change on adding acidic or basic substances?

Why some plant leaves appear red, violet or brown?

Why does hot air rise?

Explain how time was measured when pendulum clocks were not available.