NCERT Exemplar Solutions Class 9 Science Solutions for Structure of the Atom - Exercise in Chapter 4 - Structure of the Atom

Question 12 Structure of the Atom - Exercise

Rutherford’s α–particle scattering experiment showed that

(i) electrons have a negative charge

(ii) the mass and positive charge of the atom is concentrated in the nucleus

(iii) neutron exists in the nucleus

(iv) most of the space in an atom is empty Which of the above statements are correct?

(a) (i) and (iii)

(b) (ii) and (iv)

(c) (i) and (iv)

(d) (iii) and (iv


Answer is (b) (ii) and (iv)


An atom consists of a positively charged, dense, and very small nucleus that has all the protons and neutrons. The positive charge is due to protons, as neutrons have no charge. Here the space is empty because alpha particles pass straight through the gold foil without any deflection.

Thomson explained that electron s have a negative charge. The existence of neutron was discovered by Chadwick.

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