Class 9 Science - Chapter Diversity in Living Organisms NCERT Solutions | What is the criterion for classification

How do poriferan animals differ from coelenterate animals?

Explain the basis for grouping organisms into five kingdoms.

Explain how animals in Vertebrata are classified into further subgroups.

Which organisms are called primitive and how are they different from the so-called advanced organisms?

How do gymnosperms and Angiosperms differ from each other?

What are the major divisions in the Plantae? What is the basis for these divisions?

Give three examples of the range of variations that you see in life-forms around you.

Which do you think is a more basic characteristic for classifying organisms?

(a) the place where they live.
(b) the kind of cells they are made of. Why?

How do annelid animals differ from arthropods?

What are the differences between amphibians and reptiles?

Which of the following has more inertia: (a) a rubber ball and a stone of the same size? (b) a bicycle and a train? (c) a five-rupees coin and a one-rupee coin?

State the universal law of gravitation.

Which of the following are matter?

Chair, air, love, smell, hate, almonds, thought, cold, cold-drink, smell of perfume.

A force of 7 N acts on an object. The displacement is, say 8 m, in the direction of the force (Fig. 11.3). Let us take it that the force acts on the object through the displacement. What is the work done in this case?

What is meant by a pure substance?

How does the sound produced by a vibrating object in a medium reach your ear?

In a reaction, 5.3 g of sodium carbonate reacted with 6 g of ethanoic acid. The products were 2.2 g of carbon dioxide, 0.9 g water and 8.2 g of sodium observations are in agreement with the law of conservation of mass.

sodium carbonate + ethanoic acid → sodium ethanoate + carbon dioxide + water

What are canal rays?

State any two conditions essential for good health.

How is our atmosphere different from the atmospheres on Venus and Mars?

On the basis of Thomson’s model of an atom, explain how the atom is neutral as a whole.

Explain how the human ear works.

Explain how defects in a metal block can be detected using ultrasound.

A sonar device on a submarine sends out a signal and receives an echo 5 s later. Calculate the speed of sound in water if the distance of the object from the submarine is 3625 m.

Explain the working and application of a sonar.

How is ultrasound used for cleaning?

Explain how bats use ultrasound to catch a prey.

What is loudness of sound? What factors does it depend on?

A freely falling object eventually stops on reaching the ground. What happenes to its kinetic energy?

What is reverberation? How can it be reduced?