MCQs in board exams are mostly based on these topics:

1. Subatomic Particles

• Which particle has the smallest mass? (Electron)

• Which particle has a positive charge? (Proton)

• Which particle has no charge? (Neutron)

• Which particle is found in the nucleus? (Proton and neutron)

• The relative mass of a proton is approximately: (1)

• The relative mass of an electron is approximately: (1/1840)

2. Atomic and Mass Number

• Atomic number is also called: (Proton number)

• Mass number is also called: (Nucleon number)

• Number of protons = (Atomic number)

• Number of neutrons = (Mass number – Atomic number)

• Number of electrons in a neutral atom = (Number of protons)

3. Behaviour in Electric Field

• Protons are deflected towards: (Negative plate)

• Electrons are deflected towards: (Positive plate)

• Neutrons are deflected: (Not deflected at all)

4. Quantum Numbers

• The principal quantum number is represented by: (n)

• The azimuthal quantum number represents: (Sub-shell)

• The magnetic quantum number represents: (Orbital orientation)

• The spin quantum number has values: (+1/2 and –1/2)

5. Shells, Sub-shells, and Orbitals

• The maximum number of electrons in a shell is: (2n²)

• The maximum number of electrons in an s sub-shell is: (2)

• The maximum number of electrons in a p sub-shell is: (6)

• The maximum number of electrons in a d sub-shell is: (10)

• The maximum number of electrons in an f sub-shell is: (14)

6. Orbitals and Shapes

• How many orbitals are in an s sub-shell? (1)

• How many orbitals are in a p sub-shell? (3)

• How many orbitals are in a d sub-shell? (5)

• The shape of an s orbital is: (Spherical)

• The shape of a p orbital is: (Dumbbell)

7. Electronic Configuration Rules

• Electrons fill the lowest energy orbitals first: (Aufbau principle)

• No two electrons can have the same four quantum numbers: (Pauli’s exclusion principle)

• Electrons fill degenerate orbitals singly first: (Hund’s rule)

• Orbitals with the same energy are called: (Degenerate orbitals)

8. Electronic Configuration

• The electronic configuration of Na is: (1s² 2s² 2p⁶ 3s¹)

• The electronic configuration of Cl is: (1s² 2s² 2p⁶ 3s² 3p⁵)

• The electronic configuration of Mg²⁺ is: (1s² 2s² 2p⁶)

• The electronic configuration of O²⁻ is: (1s² 2s² 2p⁶)

9. Ionization Energy

• Ionization energy is the energy required to remove: (An electron from a gaseous atom)

• Ionization energy increases across a period: (True)

• Ionization energy decreases down a group: (True)

• Which element has the highest ionization energy? (Noble gas)

• Which element has the lowest ionization energy? (Alkali metal)

10. Trends in Radius

• Atomic radius decreases across a period: (True)

• Atomic radius increases down a group: (True)

• Ionic radius of a positive ion is: (Smaller than atomic radius)

• Ionic radius of a negative ion is: (Larger than atomic radius)

11. Free Radicals

• A free radical has: (One or more unpaired electrons)

• Free radicals are: (Highly reactive)

12. Shielding Effect

• Shielding effect is caused by: (Inner electrons)

• Shielding effect: (Reduces the attraction between nucleus and outer electrons)