Q1. What is the subatomic particle with a positive charge found in the nucleus of an atom?
a) Electron
b) Neutron
c) Proton
d) Nucleon
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Correct Answer: c) Proton
Explanation: Protons are subatomic particles found in the nucleus of an atom, and they carry a positive electrical charge. Along with neutrons, protons contribute to the atomic mass of an atom. The number of protons in the nucleus determines the element’s atomic number, which in turn defines the chemical properties of the element. Protons play a crucial role in the stability and identity of an atom, as they are involved in interactions with other atoms in chemical reactions.
Q2. What is the total number of electrons in a neutral atom of carbon?
a) 4
b) 6
c) 8
d) 12
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Correct Answer: b) 6
Explanation: A neutral atom of carbon contains six electrons. In an atom, the number of electrons is equal to the number of protons in the nucleus, which maintains electrical neutrality. Carbon, with an atomic number of 6, has six electrons distributed in its electron shells around the nucleus.
Q3. Which subatomic particle has a negligible mass and orbits the nucleus of an atom in specific energy levels?
a) Proton
b) Neutron
c) Electron
d) Nucleon
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Correct Answer: c) Electron
Explanation: Electrons are subatomic particles with a negligible mass compared to protons and neutrons. They orbit the nucleus of an atom in specific energy levels or electron shells. Electrons carry a negative electrical charge and play a significant role in chemical bonding and the reactivity of elements.
Q4. What is the term for the central region of an atom where protons and neutrons are located?
a) Electron cloud
b) Energy level
c) Nucleus
d) Electron shell
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Correct Answer: c) Nucleus
Explanation: The nucleus is the central region of an atom, containing protons and neutrons. It is surrounded by electron shells or energy levels where electrons orbit. The nucleus is responsible for most of the mass of an atom and determines its stability and identity.
Q5. Who proposed the planetary model of the atom with electrons orbiting the nucleus akin to planets orbiting the sun?
a) Ernest Rutherford
b) Niels Bohr
c) J.J. Thomson
d) Democritus
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Correct Answer: b) Niels Bohr
Explanation: Niels Bohr proposed the planetary model of the atom in 1913. According to this model, electrons orbit the nucleus in specific energy levels or shells, similar to the way planets orbit the sun in our solar system. This model provided a more structured understanding of atomic structure and electron behavior.
Q6. What is the term for atoms of the same element with a different number of neutrons?
a) Isomers
b) Isotopes
c) Ions
d) Elements
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Correct Answer: b) Isotopes
Explanation: Isotopes are atoms of the same element with different numbers of neutrons in their nuclei. While isotopes of an element have the same number of protons (and thus the same atomic number), they can have varying atomic masses due to differing numbers of neutrons.
Q7. Which of the following particles is NOT located in the nucleus of an atom?
a) Proton
b) Neutron
c) Electron
d) Nucleon
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Correct Answer: c) Electron
Explanation: Electrons are not located in the nucleus of an atom. Instead, they orbit around the nucleus in specific energy levels or electron shells. Protons and neutrons, collectively referred to as nucleons, are the subatomic particles found in the nucleus.
Q8. The atomic number of an element is determined by the number of which subatomic particle?
a) Protons
b) Neutrons
c) Electrons
d) Nucleons
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Correct Answer: a) Protons
Explanation: The atomic number of an element is determined by the number of protons in the nucleus of its atoms. It is represented by the letter “Z” in the periodic table and defines the element’s identity. Elements with different atomic numbers have distinct chemical properties.
Q9. What is the term for the total number of protons and neutrons in the nucleus of an atom?
a) Atomic mass
b) Atomic weight
c) Atomic number
d) Atomic radius
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Correct Answer: a) Atomic mass
Explanation: Atomic mass is the total mass of an atom, which is determined by the sum of the masses of its protons and neutrons in the nucleus. It is typically expressed in atomic mass units (amu) and is an important characteristic used to identify isotopes of an element.
Q10. Which of the following statements about electrons in an atom is true?
a) Electrons have a positive charge
b) Electrons are located in the nucleus
c) Electrons orbit the nucleus in specific energy levels
d) Electrons have a mass approximately equal to that of protons
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Correct Answer: c) Electrons orbit the nucleus in specific energy levels
Explanation: Electrons orbit the nucleus of an atom in specific energy levels or electron shells. These energy levels are quantized, meaning electrons can only occupy certain discrete energy levels within an atom. Electrons carry a negative electrical charge and have a negligible mass compared to protons and neutrons.