4-Atomic Structure

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

• 8,2,2

• 1,8,3

• 2,8,2

• 3,8,1

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

• Atomic mass

• Nucleus in the atom

• Proton

• Electron

The number of electrons in an element X is 15 and the number of neutrons is 16. Which of the following is the correct representation of the element?

• ¹⁵₁₆X

• ¹⁶₁₅X

• ³¹₁₆X

• ³¹₁₅X

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

• only (i)

• (i) and (iv)

• (ii) and (iii)

• (i) and (iii)

Which of the following are true for an element?

(i) Atomic number = number of protons + number of electrons

(ii) Mass number = number of protons + number of neutrons

(iii) Atomic mass = number of protons = number of neutrons

(iv) Atomic number = number of protons = number of electrons

• (ii) and (iv)

• (ii) and (iii)

• (i) and (iii)

• (i) and (ii)

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 uniformaly distributed in the positively charged sphere

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

• (i), (ii) and (iii)

• (i) and (iii)

• (i) and (iv)

• (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?

• (i) and (iii)

• (ii) and (iv)

• (i) and (iv)

• (iii) and (iv)

The ion of an element has 3 positive charges. Mass number of the atom is 27 and the number of neutrons is 14. What is the number of electrons in the ion?

• 13

• 10

• 14

• 16

Identify the Mg²⁺ ion from the figure where, n and p represent the number of neutrons and protons respectively.

• (a)

• (b)

• (c)

• (d)

The first model of an atom was given by

• N. Bohr

• E. Goldstein

• Rutherford

• J.J. Thomson