English Medium Class 9 - CBSE Question Bank Solutions for Science

A girl is sitting in the middle of a park of dimension 12 m × 12 m. On the left side of it, there is a building adjoining the park and on the right side of the park, there is a road adjoining the park. A sound is produced on the road by a cracker. Is it possible for the girl to hear the echo of this sound? Explain your answer.

For hearing the loudest ticking sound heard by the ear, find the angle x in Fig.12.4.

If you live in an overcrowded and poorly ventilated house, it is possible that you may suffer from which of the following diseases

Which disease is not transmitted by mosquitoes?

Which separation technique will you apply for the separation of the following?

Different pigments from an extract of flower petals.

How many atoms are present in a PO₄³⁻ ion?

What are polyatomic ions? Give examples.

Calculate the number of aluminium ions present in 0.051 g of aluminium oxide.

(Hint: The mass of an ion is the same as that of an atom of the same element. Atomic mass of Al = 27 u)

Write the distribution of electrons in carbon and sodium atoms?

If K and L shells of an atom are full, then what would be the total number of electrons in the atom?

Summarize the rules for writing of distribution of electrons in various shells for the first eighteen elements.

Na⁺ has completely filled K and L shells. Explain.

Which one of the following is a correct electronic configuration of sodium?

Name the tissue responsible for movement in our body.

Give three features of cardiac muscles.

Diagrammatically, show the difference between the three types of muscle fibres.

What is the specific function of the cardiac muscle?

Differentiate between striated, unstriated and cardiac muscles on the basis of their structure and site/location in the body.

What is immunisation?

What are the immunisation programmes available at the nearest health centre in your locality? Which of these diseases are the major health problems in your area?