Class 11 Chemistry Chapter 2 Structure of Atom MCQs

Class 11 chemistry MCQs with answers are provided here for chapter 2 Structure of Atom. These MCQs are based on the CBSE board curriculum and correspond to the most recent Class 11 chemistry syllabus. By practising these Class 11 Multiple choice questions, students will be able to quickly review all of the ideas covered in the chapter and prepare for the Class 11 Annual examinations as well as other entrance exams such as NEET and JEE.

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Class 11 Structure of Atom MCQs

1. Neutron was discovered by ————–

(a) J.J Thomson

(b) Chadwick

(c) Rutherford

(d) Priestley

Ans: (b) Chadwick

Solution: Chadwick (1932) discovered the neutral particles Neutron.

2. The nucleus of the atom consists of ————–

(a) Protons and neutrons

(b) Protons and electrons

(c) Neutrons and electrons

(d) Protons, neutrons and electrons

Ans: (a) Protons and neutrons

Solution: The nucleus of the atom consists of protons and neutrons.

3. The radius of an atomic nucleus is of the order of————–

(a) 10^-10 cm

(b) 10^-13 cm

(c)10^-15 cm

(d) 10^-8 cm

Ans: (b) 10^-13 cm

Solution: The radius of an atomic nucleus is of the order of 10^-13 cm.

4. Isotopes of an element have ————–

(a) Different chemical and physical properties

(b) Similar chemical and physical properties

(c) Similar chemical but different physical properties

(d) Similar physical but different chemical properties

Ans: (c) Similar chemical but different physical properties

Solution: Atoms of the same element which have the same atomic number but different mass number are called isotopes. So they have Similar chemicals but different physical properties.

5. Which of the following pairs represents isobars?

(a) ³He₂ and ⁴He₂

(b) ²⁴Mg₁₂ and ²⁵Mg₁₂

(c) ⁴⁰K₁₉ and ⁴⁰Ca₂₀

(d) ⁴⁰K₁₉ and ³⁹K₁₉

Ans: (c) ⁴⁰K₁₉ and ⁴⁰Ca₂₀

Solution: Atoms of different elements that have the same mass number but different atomic number are called isobars.

6. The atomic orbital is ————–

(a) The circular path of the electron

(b) Elliptical shaped Orbit

(c) Three-dimensional field around nucleus

(d) The region in which there is a maximum probability of finding an electron

Ans: (d)

Solution: The region in which there is a maximum probability of finding an electron is called orbital.

7. Principal, Azimuthal and magnetic quantum numbers are respectively related to:

(a) Size, shape and orientation

(b) Shape, size and orientation

(c) Size, orientation and shape

(d) None of the above

Ans: (a) Size, shape and orientation

Solution: Principal, Azimuthal and magnetic quantum numbers are respectively related to Size, shape and orientation.

8. The electronic configuration of chromium (Z=24) is:

(a) [Ne] 3s² 3p⁶ 3d⁴ 4s²

(b) [Ne] 3s² 3p⁶ 3d⁵ 4s¹

(c) [Ne] 3s² 3p⁶ 3d¹ 4s²

(d) [Ne] 3s² 3p⁶ 4s² 4p⁴

Ans: (b) [Ne] 3s² 3p⁶ 3d⁵ 4s¹

Solution: The electronic configuration of chromium (Z=24) is [Ne] 3s² 3p⁶ 3d⁵ 4s¹.

9. According to Aufbau principle a new electron enters the orbitals when:

(a) (n + l) is minimum

(b) (n + l) is maximum

(c) (n + m) is minimum

(d) (n + m) is maximum

Ans: (a) (n + l) is minimum

Solution: According to the Aufbau principle a new electron enters the orbitals when (n + l) is minimum. So the 4s orbital filled first then the 3d orbital.

10. Which of the following is not permissible?

(a) n= 4, l = 3, m= 0

(b) n= 4, l = 2, m= 1

(c) n= 4, l = 4, m= 1

(d) n= 4, l = 0, m= 0

Ans: (c) n= 4, l = 4, m= 1

Solution: The value of the Azimuthal quantum number always lies between 0 to n-1. If n=4, then l= 4 not possible.

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