English Medium कक्षा १० - CBSE Question Bank Solutions for Science

Why covalent compounds are different from ionic compounds?

List three characteristic properties of covalent compounds.

Give reason to justify the following: The existence of decomposers is essential in a biosphere.

Give reason to justify the following: Flow of energy in a food chain is unidirectional.

List two biotic components of a biosphere.

Why are green plants called producers?

The first trophic level in a food chain is always a green plant. Why ?

List two main components of ecosystem?

We do not clean natural ponds or lakes but an aquarium needs to be cleaned regularly. Why is it so ? Explain.

Explain why carbon forms compounds mainly by covalent bond.

List two important roles play in the environment by decomposers.

Elements forming ionic compounds attain noble gas configuration by either gaining or losing electrons from their outermost shells. Give reason to explain why carbon cannot attain noble gas configuration in this manner to form its compounds.

Name the type of bonds formed in ionic compounds and in the compounds formed by carbon.

Give reason why carbon compounds are generally poor conductors of electricity.

"Our food grains such as wheat and rice, the vegetables and fruits and even meat are found to contain varying amounts of pesticide residues." State the reason to explain how and why it happens?

State the reason why carbon can neither form C⁴⁺ cations nor C⁴⁻ anions but forms covalent compound.

State the reason to explain why covalent compounds "are bad conductors of electricity".

State the reason to explain why covalent compounds "have low melting and boiling points."

Why should a magnesium ribbon be cleaned before it is burnt in air?

What is a balanced chemical equation? Why should a chemical equation be balanced?