Please refer to Chapter 4 Structure Of The Atom MCQ Class 9 Science with answers below. These multiple-choice questions have been prepared based on the latest NCERT book for Class 9 Science. Students should refer to MCQ Questions for Class 9 Science with Answers to score more marks in Grade 9 Science exams. Students should read the chapter Structure Of The Atom and then attempt the following objective questions.

MCQ Questions Class 9 Science Chapter 4 Structure Of The Atom

The Structure Of The Atom MCQ Class 9 Science provided below covers all important topics given in this chapter. These MCQs will help you to properly prepare for exams.

Question. Atoms of the same element having different mass numbers are known as
a. isotopes.
b. isobars.
c. isotones.
d. isodiaphers.

Question. Protium, deuterium and tritium are the isotopes of
a. hydrogen.
b. carbon.
c. oxygen.
d. sulphur.

Question. Which of the following postulates of Thomson’s model of an atom is not true?
a. Thomson’s model of an atom is similar to that of Christmas pudding.
b. An atom consists of a positively charged sphere with electrons embedded in it.
c. In an atom, the magnitude of positive charge is equal to the magnitude of negative charge.
d. An atom carries a net positive charge.

Question. In Rutherford’s alpha-particle scattering experiment, a thin foil was bombarded with a stream of fast moving alpha particles.
a. iron
b. aluminium
c. gold
d. silver

Question. Rutherford’s model of an atom could not explain the
a. electrical neutrality of an atom.
b. distribution of electrons in an atom.
c. distribution of positive charge in an atom.
d. stability of an atom.

Question. Who discovered the neutron?
a. E Goldstein
b. E Rutherford
c. J J Thomson
d. J Chadwick

Question. The term ‘electron’ was first coined by
a. Michael Faraday.
b. G J Stoney.
c. J J Thomson.
d. Ernest Rutherford.

Question. An electron has mass equal to times that of a hydrogen atom.
a. 1837
b. 1/1837
c. 1528
d. 1/1528

Question. What is the valency of argon?
a. 8
b. 6
c. 2
d. 0

Question. Which of the following statements about isotopes is incorrect?
a. Isotopes are the atoms of the same element.
b. Isotopes have the same atomic number.
c. Isotopes have different mass numbers.
d. Isotopes have different chemical properties.

Question. The atomic number of an element is 18 and its mass number is 40. Which of the following elements has the same number of neutrons as X?
a. ⁴⁰₂₀Ca
b. ⁴⁰1₉K
c. ⁴¹₂₀Ca
d. ⁴¹₁₉K

Question. What is the electronic configuration of carbon?
a. 2, 4
b. 2, 3
c. 2, 2
d. 2, 1

Question. Which of the following elements has the electronic configuration 2, 5?
a. Boron
b. Nitrogen
c. Oxygen
d. Fluorine

Question. The maximum number of electrons that can be accommodated in the outermost orbit of an atom is
a. 2.
b. 4.
c. 6.
d. 8.

Question. What are the atoms of different elements having the same mass number called?
a. Isotopes
b. Isobars
c. Isotones
d. Isodiaphers

Question. The elements given in which of the following options are isobars?
a. ¹²₆C, ¹³₆C
b. ³⁵₁₇Cl, ³⁷₁₇Cl
c. ⁴⁰₁₈Ar, ⁴⁰₂₀Ca
d. ³⁶₁₆S, ³⁹₁₉K

Question. The electronic configuration of an element is 2, 8, 3. What will be the valency of this element?
a. 2
b. 3
c. 5
d. 8

Question. What is the valency of an element whose electronic configuration is 2, 8, 7?
a. 8
b. 7
c. 2
d. 1

Question. In the alpha-particle scattering experiment, most of the alpha particles
a. passed undeflected through the gold foil.
b. were deflected by small angles.
c. were deflected by large angles.
d. were deflected by 180°.

Question. Which of the following postulates of the Rutherford’s model of an atom is incorrect?
a. An atom contains a positively charged centre called the nucleus.
b. Nearly all the mass of the atom is concentrated in the nucleus.
c. The electrons revolve around the nucleus in circular paths.
d. The size of the nucleus is comparable to the size of the atom.

Question. Which of the following species does not have the electronic configuration 2, 8, 8?
a. Ar atom
b. K⁺ ion
c. Cl^– ion
d. K atom

Question. The total number of protons present in the nucleus of an atom is equal to its
a. atomic number.
b. atomic mass.
c. mass number.
d. valency.

Question. The average atomic mass of chlorine is
a. 35 u.
b. 35.5 u.
c. 37 u.
d. 39 u.

Question. The isotope of is used in the treatment of goitre.
a. hydrogen
b. cobalt
c. iodine
d. phosphorus

Question. The electronic configuration of potassium is
a. 2, 8, 9.
b. 2, 9, 8.
c. 2, 8, 8, 1.
d. 2, 8, 8, 2.

Question. has completely filled outermost shell.
a. Carbon
b. Nitrogen
c. Fluorine
d. Neon

Question. The mass number of an element X with the electronic configuration 2, 8, 1 is 25. The number of neutrons present in element X is
a. 11.
b. 14.
c. 25.
d. 37.

Question. An element has three electrons in its third shell which is also its valence shell. If the number of neutrons present in the element are 14, what is the mass number of the element?
a. 3
b. 13
c. 14
d. 27

Question. Which of the following is the correct representation of a neutron?
a. ⁰₀n
b. ¹₀n
c. ⁰₁n
d. ¹₁n

Question. What is the maximum number of electrons that can be accommodated in the fourth orbit of an atom?
a. 8
b. 16
c. 32
d. 50

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