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Test: Structure of the Atom- Assertion & Reason Type Questions - Class 9 MCQ


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15 Questions MCQ Test Science Class 9 - Test: Structure of the Atom- Assertion & Reason Type Questions

Test: Structure of the Atom- Assertion & Reason Type Questions for Class 9 2024 is part of Science Class 9 preparation. The Test: Structure of the Atom- Assertion & Reason Type Questions questions and answers have been prepared according to the Class 9 exam syllabus.The Test: Structure of the Atom- Assertion & Reason Type Questions MCQs are made for Class 9 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Test: Structure of the Atom- Assertion & Reason Type Questions below.
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Test: Structure of the Atom- Assertion & Reason Type Questions - Question 1

Direction: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : Isotopes are electrically neutral.

Reason : Isotopes are species with same mass number but different atomic numbers.

Detailed Solution for Test: Structure of the Atom- Assertion & Reason Type Questions - Question 1
Isotopes are species with same atomic number but different mass numbers.
Test: Structure of the Atom- Assertion & Reason Type Questions - Question 2

Direction: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : Atom is electrically neutral.

Reason : A neutral particle, neutron is present in the nucleus of atom.

Detailed Solution for Test: Structure of the Atom- Assertion & Reason Type Questions - Question 2
Atom is electrically neutral because the number of protons (positively charged particle) is equal to the number of electrons (negatively charged particle).
Test: Structure of the Atom- Assertion & Reason Type Questions - Question 3

Direction: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : Isotopes are electrically neutral.

Reason : Isotopes of an element have equal number of protons and electrons.

Detailed Solution for Test: Structure of the Atom- Assertion & Reason Type Questions - Question 3
Isotopes are electrically neutral because they possess an equal number of protons (+) and electrons (-).
Test: Structure of the Atom- Assertion & Reason Type Questions - Question 4

Direction: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : The size of the nucleus is very small as compared to the size of the atom.

Reason : The electrons revolve around the nucleus of the atom.

Detailed Solution for Test: Structure of the Atom- Assertion & Reason Type Questions - Question 4
The nucleus of an atom is about 10-15 m in size; this means it is about 10-5 (or 1/100,000) of the size of the whole atom. A good comparison of the nucleus to the atom is like a pea in the middle of a racetrack. (10-15 m is typical for the smaller nuclei; larger ones go up to about 10 times that.)
Test: Structure of the Atom- Assertion & Reason Type Questions - Question 5

Direction: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : In Rutherford’s gold foil experiment, very few α -particles are deflected back.

Reason : Nucleus present inside the atom is heavy.

Detailed Solution for Test: Structure of the Atom- Assertion & Reason Type Questions - Question 5
Nucleus present inside the atom is heavy but small.
Test: Structure of the Atom- Assertion & Reason Type Questions - Question 6

Direction: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : Thomson’s atomic model is known as ‘raisin pudding’ model.

Reason : The atom is visualized as a pudding of positive charge with electrons (raisins) embedded in it.

Detailed Solution for Test: Structure of the Atom- Assertion & Reason Type Questions - Question 6
In 1897, J.J. Thomson discovered the first subatomic particle, the electron, while researching cathode rays. To explain the neutrality of atoms, Thomson proposed a model of the atom in which negative electrons are scattered throughout a sphere of positive charge. He called his atom the raisin-pudding model.

Therefore, both assertion and reason are correct and the reason is the correct explanation for assertion.

Test: Structure of the Atom- Assertion & Reason Type Questions - Question 7

Direction: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : Isobars are identical in chemical properties.

Reason : Isobars have same atomic number.

Detailed Solution for Test: Structure of the Atom- Assertion & Reason Type Questions - Question 7

Isobars are not identical in chemical properties because they have same mass number and different atomic numbers.

Test: Structure of the Atom- Assertion & Reason Type Questions - Question 8

Direction: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:
Assertion: Electron move away from a region of higher potential to a region of lower potential. 
Reason: An electron has a negative charge. 

Detailed Solution for Test: Structure of the Atom- Assertion & Reason Type Questions - Question 8

Direction of electric field is from region of high potential to low potential & electron or any -ve charged particle will move against the field or lower potential to higher potential. 

Test: Structure of the Atom- Assertion & Reason Type Questions - Question 9

Direction: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : Anions are larger in size than the parent atom.

Reason : In an anion, the number of protons in the nucleus is less than the number of electrons moving around it.

Detailed Solution for Test: Structure of the Atom- Assertion & Reason Type Questions - Question 9
The size of an anion is larger than its parent atom because anions are formed due to the gain of electrons. When the electrons increase, there are still the same number of protons. The attractive force is thus reduced as there are the same number of protons attracting an increased number of electrons.
Test: Structure of the Atom- Assertion & Reason Type Questions - Question 10

Direction: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : A few positively charged a -particles are deflected in Rutherford’s experiment.

Reason : Most of the space in the atom is empty.

Detailed Solution for Test: Structure of the Atom- Assertion & Reason Type Questions - Question 10
The positive charge has to be concentrated in a very small volume (nucleus) that repelled and deflected the positively charged α -particles.
Test: Structure of the Atom- Assertion & Reason Type Questions - Question 11

Direction: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : Cathode rays travel in straight lines.

Reason : Cathode rays do not penetrate through thin sheets.

Detailed Solution for Test: Structure of the Atom- Assertion & Reason Type Questions - Question 11
Cathode rays can penetrate through thin sweets.
Test: Structure of the Atom- Assertion & Reason Type Questions - Question 12

Direction: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : Isotopes of an element show different valencies.

Reason : Isotopes have different atomic numbers.

Detailed Solution for Test: Structure of the Atom- Assertion & Reason Type Questions - Question 12

Isotopes have the same number of electrons. Hence, their valencies do not differIsotopes have the same atomic number but different atomic mass numbers: The total number of protons present in the atomic nucleus is known as its atomic number whereas the mass number is defined as the total number of protons and neutrons present in the atomic nucleus.

Test: Structure of the Atom- Assertion & Reason Type Questions - Question 13

Direction: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : Bohr’s orbits are called stationary orbits.

Reason : Electrons remain stationary in these orbits for sometime.

Detailed Solution for Test: Structure of the Atom- Assertion & Reason Type Questions - Question 13
Electrons in different orbits have fixed energies.
Test: Structure of the Atom- Assertion & Reason Type Questions - Question 14

Direction: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : The atoms of different elements having same mass number but different atomic numbers are known as isobars.

Reason : The sum of protons and neutrons, in the isobars is always different.

Detailed Solution for Test: Structure of the Atom- Assertion & Reason Type Questions - Question 14
Sum of protons and neutrons is known as mass number which is same for isobars.
Test: Structure of the Atom- Assertion & Reason Type Questions - Question 15

Direction: In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:
Assertion: Members of noble gas family are very little reactive chemically.
Reason: Members of noble gas family have completely filled valence shells of their atoms.

Detailed Solution for Test: Structure of the Atom- Assertion & Reason Type Questions - Question 15

The correct option is A

Both assertion and reason are correct and the reason is the correct explanation of assertion.

Explanation for assertion:

Group 18 elements are called inert gases, as they do not react easily.

Explanation for reason statement:

  1. Noble gas elements have their duplet or octet complete, which means that they have completely filled valence shells.
  2. Due to this reason, they have very low electronegativity and very high Ionization Potential, hence they are then fairly unreactive and called inert gases.

Hence, A) Both assertion and reason are true, reason is the correct explanation of assertion.

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