Structure of atoms

What is the shape of atom?

• square

• circle

• sphare

• triangle

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

• 3, 8, 1

• 2, 8, 2

• 2, 8, 2

• 2, 8, 2

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

• electron

• proton

• nucleus in the atom

• atomic mass

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

The first model of an atom was given by?

• N. Bohr

• E. Goldstein

• Rutherford

• J.J. Thomson

An atom with 3 protons and 4 neutrons will have a valency of?

• 3

• 7

• 1

• 5

Hydrogen exists in three isotopic forms, 11H, 21H, 31H known as protium, deuterium and tritium. Why are all the isotopes neutral in nature?

• Since neutrons are neutral in nature hence isotopes are electrically neutral.

• All the isotopes have one electron and one proton, hence they are neutral.

• All the isotopes have one proton and one neutron, hence they are neutral

• Increasing number of protons in the isotopes make them neutral.

An alpha particle is also known as:

• subatomic particle

• an unionised helium atom

• a neutral particle

• a doubly-charged helium ion

Isobars do not differ in the number of

• protons

• electrons

• neutrons

• nucleons

the charge on an electron is equal to:

• 1.6 × 10^-19 C of -ve charge

• 2.6 × 10^-19 C of -ve charge

• 1.6 × 10^-22 C of -ve charge

• 1.6 × 10^-23 C of -ve charge