Atoms MCQs
Atoms MCQs
Q.1: When alpha particles are sent through a thin gold foil, most of them go straight through the foil, because
[A] Alpha particles are positively charged
[B] Mass of alpha particle is more than mass of electron
[C] Most of the part of an atom is empty space
[D] Alpha particles moves with high velocity
[C] Most of the part of an atom is empty space
Q.2: The radius of an atomic nucleus have an order of,
[A] 10-8m
[B] 10-15m
[C] 10-12m
[D] 10-10m
[B] 10-15m
Q.3: The existence of positively charged nucleus was established by,
[A] Bohr’s model of H-atom
[B] Positive ray analysis
[C] α-Scattering experiment
[D] Thomson’s model of atom
[C] α-Scattering experiment
Q.4: Which spectral series of hydrogen lie in UV region.
[A] Paschen series
[B] Balmer series
[C] Brackett
[D] Lyman series
[D] Lyman series
Q.5: In equation En= -13.6/𝑛2, what does this negative sign indicates.
[A] Electrons are free to move
[B] Electron is bound with nucleus
[C] Kinetic energy is equal to potential energy
[D] Atom is radiating energy
[B] Electron is bound with nucleus
Q.6: The monochromatic beams A and B of equal intensities I, hit a screen. The number of photons hitting the screen by beam A is twice that by beam B. The ratio of their frequencies will be –
[A] 1:2
[B] 2:1
[C] 1:1
[D] 1:3
[A] 1:2
Q.7: Which of the following has maximum stopping potential when metal is illuminated by visible light?
[A] Blue
[B] Yellow
[C] Violet
[D] Red
[C] Violet
Q.8: The threshold wavelength for a metal having work function ϕ0 is λ0 , what is the threshold wavelength for a metal whose work function is ϕ0 /2 .
[A] 4 λ0
[B] 2 λ0
[C] λ0 /2
[D] λ0 /4
[B] 2 λ0
Q.9: Maximum kinetic energy of emitted electron depends on the frequency of incident photon
when frequency of incident photons is
[A] equal to the threshold frequency
[B] half of threshold frequency
[C] greater then threshold frequency
[D] one third of threshold frequency
Q.10: Two particles have equal momentum. What is the ratio of their de-Broglie wavelength?
[A] 2
[B] 1
[C] 3
[D] 0.5
Other basic Conceptual Questions
Q: What is an atom?
Answer: An atom is the smallest unit of matter that retains the chemical properties of an element. It is composed of subatomic particles, including protons, neutrons, and electrons.
Q: What is the atomic structure?
Answer: The atomic structure refers to the organization and arrangement of subatomic particles within an atom. It consists of a nucleus, which contains protons and neutrons, and electrons that orbit the nucleus in specific energy levels or electron shells.
Q: What are the subatomic particles in an atom?
Answer: An atom has three main subatomic particles: protons, neutrons, and electrons. Protons carry a positive charge, neutrons have no charge (they are neutral), and electrons carry a negative charge.
Q: What is the function of protons in an atom?
Answer: Protons are positively charged particles found in the nucleus of an atom. They determine the atomic number of an element and contribute to the overall positive charge of the nucleus. The number of protons in an atom defines the identity of the element.
Q: What is the function of neutrons in an atom?
Answer: Neutrons are neutral particles found in the nucleus of an atom. They do not carry any charge but contribute to the mass of the atom. Neutrons help stabilize the nucleus and can influence the stability and isotopes of an element.
Q: What is the function of electrons in an atom?
Answer: Electrons are negatively charged particles that orbit the nucleus of an atom in specific energy levels or electron shells. They are involved in chemical bonding and determine the reactivity and properties of an element. Electrons are responsible for the formation of chemical bonds and the interactions between atoms.
Q: What is the overall charge of an atom?
Answer: The overall charge of an atom is neutral. This means that the number of protons, which carry a positive charge, is equal to the number of electrons, which carry a negative charge. The positive charge of the protons in the nucleus is balanced by the negative charge of the orbiting electrons.
Q: What determines the identity of an atom?
Answer: The identity of an atom is determined by the number of protons in its nucleus, which is referred to as the atomic number. Each element has a unique atomic number. For example, atoms with six protons are carbon atoms, and atoms with eight protons are oxygen atoms.
Q: What are energy levels or electron shells?
Answer: Energy levels, also known as electron shells, are regions surrounding the nucleus of an atom where electrons are found. These shells are designated by numbers (1, 2, 3, etc.) or letters (K, L, M, etc.). Electrons occupy the lowest energy level available before moving to higher energy levels.
Q: Can electrons move between energy levels?
Answer: Yes, electrons can move between energy levels by absorbing or releasing energy. When electrons gain energy, they can move to higher energy levels (excited state), and when they release energy, they move back to lower energy levels (ground state). This energy transfer is involved in various chemical processes, including the emission and absorption of light.
Q: What is an electron configuration?
Answer: An electron configuration describes the arrangement of electrons within an atom's energy levels or electron shells. It follows a specific pattern based on the number of electrons and the rules governing electron distribution in orbitals.
Q: How do atoms form ions?
Answer: Atoms form ions by gaining or losing electrons. When an atom loses one or more electrons, it becomes a positively charged ion called a cation. Conversely, when an atom gains one or more electrons, it becomes a negatively charged ion called an anion. Ion formation occurs to achieve a more stable electron configuration.
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