In 1808, Dalton, a British school teacher, proposed that matter was made up of extremely small indivisible particles known as atoms. For a number of years, the concept grew steadily. However, studies conducted by eminent scientists such as J.J Thomson, Rutherford, Bohr, and Chadwick established that an atom is not the smallest indivisible particle but is made up of smaller particles such as electrons, protons, neutrons, and so on.
Download Class 9 Chemistry Worksheet on Chapter 4 Structure of the Atom Set 1 PDF
CBSE Class 9 Chemistry Chapter 4 Structure of the Atom– Set 1
Q-1: What is the distinction between atomic mass and mass number?
Q-2: Calculate the approximate charge in coulombs and mass in kilograms of the sodium-23 nucleus.
Q-3: Proton was discovered by
a) Thomson’s
b) Goldstein
c) Rutherford
d) Chadwick
Q-4: Rutherford’s scattering experiment lead to the discovery of
a) Electrons
b) Nucleus
c) Atom
d) alpha-particles
Q-6: The nucleus of deuterium contains
a) 1p + 1 e–
b) 2p + 0n
c) 1p + 1n
d) 2p + 2n
Q-7:Which of the following electron-related statements is false?
a) It is a component of cathode rays
b) It is a negatively charged particle
c) An electron has the same mass as a neutron.
d) It is a fundamental constituent of all atoms.
Q-8: How will you determine the valency of the following?
a) Calcium
b) Oxygen
c) Neon
Q-9: Which of the following does not exhibit path deflection when passing through an electric field? Proton, electron, cathode rays, neutrons, alpha particles
Q-10: Find the number of valence electrons in the following
a) Na+
b) Cl–
d) C
Q-11: What are the various uses of isotopes?
Q-12:
a) What is Thomson’s model of atom?
b) Why are Bohr’s orbits called stationary orbits?
Q-13: Complete the following table:
| Particle | Atomic number | Neutrons | Protons | Electrons | Mass number |
|---|---|---|---|---|---|
| Aluminium ion | 13 | 10 | |||
| Nitrogen atom | 7 | 7 | |||
| Phosphorus Atom | 15 | 31 | |||
| Bromine | 45 | 80 | |||
| Calcium ion | 20 | 20 |
Q-14: Which of the following electron configurations is correct for a magnesium atom?
a) 2,8
b) 2,2,8
c) 2,8,2
d) 8,2,2.
Q-15: What is the maximum number of electrons that an M-shell can hold?
a) 8
b) 18
c) 16
d) 32
Q-16:
Assertion: All isotopes of the given element show the same type of chemical behaviour
Reason: The chemical properties of an atom are controlled by the number of electrons in the atom.
a) Both A and R are true and R is the correct explanation of A.
b) Both A and R are true and R is not the correct explanation of A.
c) A is true and R is false
d) Both A and R are false
Q-17: In each of the following cases, identify the element:
i) An element’s trivalent anion with ten electrons
ii) An element’s trivalent cation with ten electrons
What is the name of the relationship between the two ions?
Q-18: Fill in the blanks
a) Elements are defined by the number of ________ they possess.
b) ___________ is the combining capacity of an atom.
c) The mass of a proton is _______- unit.
d) The chemical properties of isobars are _________.
e) According to Dalton’s atomic theory an atom is ________ and _______.
Q-19: What do you mean by canal rays?
Q-20: Write the correct symbol for the atom with the given atomic number(Z) and atomic mass(A).
i) Z=9, A=19
II) Z= 92, A= 233
III) Z=3, A=7
Download the PDF to access answers to the Chemistry Worksheet for Class 9 Chemistry Chapter 4 Structure of the Atom Set – 1
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Read Also:
- Atoms and Molecules
- Rutherford’s Atomic Model and Limitations
- Thomson’s Atomic Model
- Thomson’s Atomic Model and its Limitations
- Class 9 Structure of the Atom MCQ
- Class 9 Structure of the Atom Important Questions with Answers
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