Acids, Bases and Salts — Science STD 10 — Question

Explain why:
Covalent compounds have generally low melting points.

Why are vegetable oils healthy as compared to vegetable ghee? How are vegetable oils converted into vegetable ghee? Name the process.

State Mendeleev’s periodic law.

Where should hydrogen be placed in the modern periodic table? Give reason for your answer.

What happens during a bee sting? What is its remedy?

A mixture of ethyne (acetylene) and oxygen is burnt for welding. Can you tell why a mixture of ethyne and air is not used?

A student added few pieces of aluminium metal to two test tubes A and B containing aqueous solutions of iron sulphate and copper sulphate. In the second part of her experiment, she added iron metal to another test tubes C and D containing aqueous solutions of aluminium sulphate and copper sulphate.

In which test tube or test tubes will she observe colour change? On the basis of this experiment, state which one is the most reactive metal and why.

Give any two differences between soaps and detergents.

Why do we store silver chloride in dark coloured bottles?

 Explain the following in terms of gain or loss of oxygen with one example:

1. Oxidation.
2. Reduction.