Atomic structure - Grade 9

Which of the following correctly represent the electronic distribution in the Mg atom?

• (a) 3, 8, 1

• (b) 2, 8, 2

• (c) 1, 8, 3

• (d) 8, 2, 2

Rutherford’s ‘alpha (α) particles scattering experiment’ resulted in to discovery of

• (a) Electron

• (b) Proton

• (c) Nucleus in the atom

• (d) Atomic mass

Which of the following statements about Rutherford’s model of atom are correct?

(i) considered the nucleus as positively charged

(ii) established that the α–particles are four times as heavy as a hydrogen atom

(iii) can be compared to solar system

(iv) was in agreement with Thomson’s model

• (a) (i) and (iii)

• (b) (ii) and (iii)

• (c) (i) and (iv)

• (d) only (i)

In the Thomson’s model of atom, which of the following statments are correct?

(i) the mass of the atom is assumed to be uniformaly distributed over the atom

(ii) the positive charge is assumed to be uniformaly distributed over the atom

(iii) the electrons are scatterd in the positively charged sphere

(iv) the electrons attract each other to stabilise the atom

• (a) (i), (ii) and (iii)

• (b) (i) and (iii)

• (c) (i) and (iv)

• (d) (i), (iii) and (iv)

Rutherford’s α–particle scattering experiment showed that

(i) electrons have 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 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)

The first model of an atom was given by

• (a) N. Bohr

• (b) E. Goldstein

• (c) Rutherford

• (d) J.J. Thomson

The electron distribution in an aluminium atom is

• (a) 2, 8, 3

• (b) 2, 8, 2

• (c) 8, 2, 3

• (d) 2, 3, 8

Which of the following in Fig. do not represent Bohr’s model of an atom correctly?

• i

• ii

• iii

• iv

Atomic number and symbol of sodium is

• Na - 10

• Ne-10

• Na - 11

• S - 11

Which of the following pair of symbol and atomic number of an element is correct?

• K-17

• F-9

• C-20

• Si - 15