Important Questions for CBSE Class 12 Physics Chapter 12 – Atoms

The important Questions for CBSE Class 12 Physics Chapter 12 covered all the important topics covered in this article. Students are introduced to the concepts of modern physics in Chapter 12 of Physics Class 12. The atoms and nuclei Class 12 important questions give a better understanding of the concepts for students. The Class 12 Physics Chapter 12 important questions are prepared by the subject matter experts with respect to the updated CBSE syllabus.

Multiple Choice Questions

1. Which subatomic particle has a positive charge?
A) Proton
B) Electron
C) Neutron
D) Positron

Answer: A) Proton
Reason: Protons have a positive charge, while electrons have a negative charge and neutrons have no charge.

2. What is the atomic number of an element determined by?
A) Number of protons
B) Number of neutrons
C) Number of electrons
D) Atomic mass

Answer: A) Number of protons
Reason: The atomic number of an element is equal to the number of protons in its nucleus.

3. Which of the following particles is located outside the nucleus of an atom?
A) Proton
B) Electron
C) Neutron
D) Positron

Answer: B) Electron
Reason: Electrons are located in the electron cloud surrounding the nucleus of an atom.

4. What is the charge of a neutron?
A) Positive
B) Negative
C) Neutral
D) Variable

Answer: C) Neutral
Reason: Neutrons have no charge, they are neutral particles.

5. Which subatomic particle has the least mass?
A) Proton
B) Electron
C) Neutron
D) Positron

Answer: B) Electron
Reason: Electrons have much less mass compared to protons and neutrons.

6. What is the total number of protons and neutrons in the nucleus of an atom called?
A) Atomic number
B) Atomic mass
C) Mass number
D) Isotopic mass

Answer: C) Mass number
Reason: The mass number is the sum of the number of protons and neutrons in the nucleus of an atom.

7. Which scientist is credited with the discovery of the electron?
A) J.J. Thomson
B) Ernest Rutherford
C) Niels Bohr
D) Marie Curie

Answer: A) J.J. Thomson
Reason: J.J. Thomson discovered the electron using cathode ray tube experiments.

8. What is the maximum number of electrons that can occupy the first energy level of an atom?
A) 2
B) 4
C) 6
D) 8

Answer: A) 2
Reason: The first energy level can hold a maximum of 2 electrons.

9. Which of the following elements has the smallest atomic radius?
A) Lithium
B) Sodium
C) Potassium
D) Rubidium

Answer: A) Lithium
Reason: Atomic radius generally decreases as you move from left to right across a period in the periodic table.

10. How many electrons are present in a neutral atom of oxygen?
A) 6
B) 7
C) 8
D) 9

Answer: C) 8
Reason: Oxygen has 8 electrons in a neutral atom, as it has 8 protons to maintain neutrality.

Short Answers Type Questions

Ques. What is the basic unit of matter?
Ans. The atom is the fundamental building block of matter, consisting of a nucleus and electrons.

Ques. How many protons are in a helium atom?
Ans. Helium has 2 protons in its nucleus, giving it an atomic number of 2.

Ques. Define an electron’s role in an atom.
Ans. Electrons orbit the nucleus in energy levels, determining the atom’s chemical properties.

Ques. What are isotopes?
Ans. Isotopes are atoms of the same element with different numbers of neutrons, leading to varied atomic masses.

Ques. Explain the concept of atomic mass.
Ans. Atomic mass is the average mass of all isotopes of an element, considering their abundance.

Ques. How do electrons distribute in energy levels?
Ans. Electrons fill energy levels closest to the nucleus first before moving to higher levels.

Ques. Describe the composition of an atom’s nucleus.
Ans. The nucleus contains protons and neutrons, contributing to the atom’s mass and identity.

Ques. What determines an element’s identity?
Ans. The number of protons in an atom’s nucleus defines its atomic number and element type.

Ques. What are atoms and how do they form the building blocks of matter?
Ans. Atoms are the basic units of matter that make up everything in the universe. They consist of a nucleus, which contains protons and neutrons, surrounded by electrons. Atoms combine with each other through chemical bonds to form molecules, which in turn make up all the substances we encounter in our daily lives.

Ques. How do scientists study atoms and their structure?
Ans. Scientists use a variety of techniques to study atoms and their structure. One common method is spectroscopy, which involves analyzing the light emitted or absorbed by atoms to determine their composition and properties. Another technique is microscopy, which allows scientists to directly observe atoms using powerful microscopes.

Ques. What is the significance of the periodic table in understanding atoms?
Ans. The periodic table is a systematic arrangement of all known elements based on their atomic number and chemical properties. It provides a comprehensive framework for understanding the relationships between different atoms and predicting their behavior in chemical reactions. The periodic table is an essential tool for chemists and physicists to study and manipulate atoms.

Ques. How do atoms interact with each other to form compounds?
Ans. Atoms interact with each other through chemical bonds, which are formed by the sharing or transfer of electrons between atoms. These bonds can be covalent, where electrons are shared between atoms, or ionic, where electrons are transferred from one atom to another. By forming bonds, atoms can combine to create new substances with unique properties, known as compounds.

Long Answers Types Questions

Ques. What are the fundamental particles that make up an atom, and how do they contribute to its structure?
Ans. Atoms are composed of three primary particles: protons, neutrons, and electrons. Protons carry a positive charge and are located in the nucleus, along with neutrons, which have no charge. Electrons, which are negatively charged, orbit the nucleus at specific energy levels. The combination of these particles determines the overall structure and properties of an atom.

Ques. How do quantum mechanics principles influence our understanding of atomic structure and behavior?
Ans. Quantum mechanics is a branch of physics that describes the behavior of particles at the atomic and subatomic levels. It introduces concepts such as wave-particle duality, superposition, and quantization, which challenge classical notions of physics. Quantum mechanics provides a more accurate and comprehensive framework for explaining atomic phenomena, including electron behavior, energy levels, and bonding interactions. It has revolutionized our understanding of atoms and their fundamental properties.

Ques. What experimental techniques are used to investigate the behavior of atoms at the nanoscale level, and how do they contribute to advancements in nanotechnology?
Ans. Experimental techniques such as scanning tunneling microscopy (STM) and atomic force microscopy (AFM) allow scientists to observe and manipulate individual atoms and molecules at the nanoscale level. These techniques provide valuable insights into the structure, properties, and interactions of atoms in nanomaterials. By studying atoms at such small scales, researchers can develop innovative nanotechnologies with applications in electronics, medicine, energy storage, and other fields. The ability to control and engineer atoms at the nanoscale opens up new possibilities for creating advanced materials and devices with unique functionalities.

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