Atomic Structure Quiz - ICSE Class 8 Science
Free practice quiz: Atomic Structure (ICSE Class 8 Science). 50 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
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Which subatomic particle carries a positive charge and is found in the nucleus of an atom?
- Electron
- Neutron
- Proton
- Photon
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Answer: C. Proton
Protons are positively charged subatomic particles located in the nucleus of an atom. Electrons are negatively charged and orbit the nucleus. Neutrons have no charge and are also in the nucleus. Photons are particles of light.
If an atom has 8 protons and 8 neutrons, what is its mass number?
- 8
- 16
- 64
- It cannot be determined
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Answer: B. 16
The mass number is the sum of protons and neutrons. In this case, 8 protons + 8 neutrons = 16.
The nucleus of an atom contains:
- Only protons
- Only neutrons
- Protons and neutrons
- Electrons and neutrons
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Answer: C. Protons and neutrons
The nucleus of an atom is composed of positively charged protons and neutral neutrons.
What is the term for the region around the nucleus where an electron is likely to be found?
- Orbit
- Shell
- Orbital
- Energy level
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Answer: C. Orbital
In modern atomic theory (quantum mechanics), electrons are described as existing in orbitals, which are three-dimensional regions of probability where an electron is most likely to be found. While shells and energy levels describe the energy of the electron, 'orbital' is the term for the specific region.
The concept of electron shells originating from Bohr's model implies that:
- Electrons occupy a continuous range of energies.
- Electrons can be anywhere in the atom.
- Electrons occupy discrete energy levels, with specific amounts of energy.
- Electrons are stationary in their orbits.
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Answer: C. Electrons occupy discrete energy levels, with specific amounts of energy.
Bohr's model introduced the idea that electrons orbit the nucleus in specific energy levels or shells, and can only move between these levels by absorbing or emitting specific amounts of energy (quanta).