Class 9 Science - Chapter Structure of the Atom NCERT Solutions | With the help of Table 4.1, find out the

If number of electrons in an atom is 8 and number of protons is also 8, then (i) what is the atomic number of the atom? and (ii) what is the charge on the atom?

For the symbol H,D and T tabulate three sub-atomic particles found in each of them.

Explain with examples (i) Atomic number, (ii) Mass number, (iii) Isotopes and iv) Isobars. Give any two uses of isotopes.

Define valency by taking examples of silicon and oxygen.

Describe Bohr’s model of the atom.

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

Draw a sketch of Bohr’s model of an atom with three shells.

Write the electronic configuration of any one pair of isotopes and isobars.

Compare all the proposed models of an atom given in this chapter.

The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of isotopes ¹⁶₈ X and ¹⁸₈ X in the sample?

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

State any two conditions essential for good health.

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

Who discovered cells, and how?

A ball is gently dropped from a height of 20 m. If its velocity increases uniformly at the rate of 10 m s^-2, with what velocity will it strike the ground? After what time will it strike the ground?

Discuss the implications of the following statement:
“It is interesting to note that poultry is India;s most efficient converter of low fibre food stuff (which is unfit for human consumption) into highly nutritious animal protein food”.

What is pasturage and how is it related to honey production?

A bus decreases its speed from 80 km h^-1 to 60 km h^-1 in 5 s. Find the acceleration of the bus.

What management practices are common in dairy and poultry farming?

We know that many human activities lead to increasing levels of pollution of the air, water-bodies and soil. Do you think that isolating these activities to specific and limited areas would help in reducing pollution?

In the following example, try to identify the number of times the velocity of the ball changes: “A football player kicks a football to another player of his team who kicks the football towards the goal. The goalkeeper of the opposite team collects the football and kicks it towards a player of his own team”.
Also identify the agent supplying the force in each case.

Why are we normally advised to take bland and nourishing food when we are sick?

Will advanced organisms be the same as complex organisms? Why?

How are the criteria for deciding divisions in plants different from the criteria for deciding the subgroups among animals?