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Bohr's Model of an Atom - MCQ Practice Set

01. According to Bohr's model of an atom, electrons move in specific orbits called: a) Energy orbits b) Quantum orbits c) Stationary states d) Angular orbits Answer: c) Stationary states Explanation: Bohr proposed that electrons revolve around the nucleus only in certain selected circular paths called stationary states or orbits. These orbits are associated with definite energies and are also known as energy levels or quantum levels. 02. Which principle of Bohr's model states that only certain orbits are permitted in which angular momentum of the electron is a whole number multiple of h/2π? a) Stationary principle b) Quantized energy levels c) Angular momentum quantization d) Radiation emission principle Answer: c) Angular momentum quantization Explanation: Bohr's model introduced the principle of angular momentum quantization, stating that only specific orbits are allowed where the angular momentum of the electron is a whole number multiple of h/2π, where 'h' is Pl

Bohr's Model of an Atom

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Bohr's Model of an Atom, proposed by Niels Bohr in 1913, revolutionized the understanding of atomic structure and addressed the limitations of Rutherford's model. It was based on the principles of quantized energy levels and angular momentum. The important postulates are: 01. Electrons Move in Specific Orbits: The electrons revolve round the nucleus only in certain selected circular paths called orbits. These orbits are associated with definite energies and are called energy shells or energy levels or quantum levels. These are numbered as 1, 2, 3, 4 etc. (starting from the nucleus) or designated as K, L, M, N..., etc. 02. Radiation Emission and Absorption: As long as an electron remains in a particular orbit, it does not lose or gain energy. This means that energy of an electron in a particular path remains constant. Therefore, these orbits are also called stationary states. Electrons can move between different orbits by either absorbing or emitting photons of electromagneti

Rutherford's Model of Atom - MCQ Practice Set

01. What was the primary objective of Rutherford's scattering experiment? a) To investigate the chemical properties of gold atoms b) To test Thomson's Plum Pudding Model of the atom c) To study the behavior of electrons in the gold foil d) To measure the mass of α–particles Answer: b) To test Thomson's Plum Pudding Model of the atom Explanation: Rutherford's primary objective was to investigate the structure of the atom and test the Plum Pudding Model proposed by J.J. Thomson. The experiment aimed to understand how α–particles interacted with the atoms in the gold foil, which would provide insights into the atomic structure. 02. What were the observations made during Rutherford's scattering experiment? a) Most of the α–particles were absorbed by the gold foil b) A majority of the α–particles passed through the gold foil undeflected c) All α–particles were deflected by large angles d) None of the α–particles interacted with the gold foil Answer: b) A majority of the

Rutherford's Model of Atom

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Rutherford's Model of the Atom, also known as the Rutherford Model or the Planetary Model, was proposed by Ernest Rutherford in 1911. It revolutionized the understanding of atomic structure and replaced Thomson's Plum Pudding Model . Rutherford's Scattering Experiment Rutherford's scattering experiment, also known as the gold foil experiment, was conducted by physicist Ernest Rutherford and his students (Hans Geiger and Ernest Marsden) in 1909. The experiment aimed to investigate the structure of the atom and test the Plum Pudding Model proposed by J.J. Thomson. Rutherford and his students (Hans Geiger and Ernest Marsden) bombarded very thin gold foil with α–particles. A stream of high energy α–particles from a radioactive source was directed at a thin foil (about 0.00004 cm thick) of gold metal. The thin gold foil had a circular fluorescent zinc sulphide screen around it. Whenever α–particles struck the screen, a tiny flash of light was produced at that point. The res

Thomson's Plum Pudding Model of the Atom - MCQ Practice Set

01. What was the Thomson atomic model primarily aimed at describing? a) The behavior of electrons in atoms b) The distribution of positive and negative charges within atoms c) The structure of the nucleus within atoms d) The formation of chemical bonds between atoms Answer: b) The distribution of positive and negative charges within atoms Explanation: The Thomson atomic model focused on describing the internal structure of atoms, particularly the distribution of positive charge (represented as a sphere) with negatively charged electrons embedded throughout, akin to plums in a pudding. 02. Who initially proposed the Thomson atomic model? a) Joseph John Thomson b) William Thomson (Lord Kelvin) c) Ernest Rutherford d) Niels Bohr Answer: b) William Thomson (Lord Kelvin) Explanation: The Thomson atomic model was initially suggested by William Thomson, commonly known as Lord Kelvin, around 1900. 03. What did J.J. Thomson's discovery of the electron establish? a) The existence of positive

Thomson's Plum Pudding Model of the Atom

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The Thomson atomic model, proposed around 1900, is one of the earliest attempts to describe the internal structure of atoms. Initially suggested by William Thomson, commonly known as Lord Kelvin (1824 - 1907), and later supported by Sir Joseph John Thomson Commonly known as J.J. Thomson, this model was shaped by their collaborative efforts. The support of the model by Sir J.J. Thomson was particularly significant due to his groundbreaking discovery of the electron in 1897. This discovery was important because it established the existence of a negatively charged component within each atom, which radically changed the scientific understanding of the time. J.J. Thomson proposed the Plum Pudding Model in 1904 based on his experiments with cathode rays. In these experiments, Thomson observed that cathode rays, which are streams of negatively charged particles, were produced when high voltage was applied to electrodes in a vacuum tube. He concluded that these cathode rays were composed of n

Dalton's Atomic Theory - MCQ Practice Set

01. According to Dalton's atomic theory, what are atoms considered as? a) Tiny, divisible particles b) Fundamental building blocks of matter c) Mixtures of elements d) Complex compounds Answer: b) Fundamental building blocks of matter Explanation: Dalton proposed that atoms are the fundamental building blocks of matter and cannot be further divided into smaller parts while retaining their chemical properties. 02. Which principle is consistent with Dalton's postulate that atoms can be rearranged, combined, or separated in chemical reactions? a) Law of Definite Proportions b) Law of Conservation of Mass c) Law of Multiple Proportions d) Avogadro's Law Answer: b) Law of Conservation of Mass Explanation: Dalton's postulate aligns with the Law of Conservation of Mass, which states that the total mass of the reactants must equal the total mass of the products in a chemical reaction. 03. What aspect of chemical compounds does Dalton's atomic theory explain? a) Formation of

Dalton's Atomic Theory

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Dalton's atomic theory, proposed by the English physicist and chemist John Dalton in the early 19th century, is a fundamental concept in chemistry that revolutionized the understanding of matter. In 1808, Dalton published ‘A New System of Chemical Philosophy’, in which he proposed the following postulates, to explain the laws of chemical combination: Dalton proposed that all matter is composed of tiny, indivisible particles called atoms. According to this postulate, atoms are the fundamental building blocks of matter and cannot be further divided into smaller parts while retaining their chemical properties. Dalton suggested that all atoms of a particular element are identical in size, mass and chemical properties. This implies that atoms of different elements have different properties and behave differently in chemical reactions. Dalton proposed that chemical compounds are formed when atoms of different elements combine in fixed, simple, whole-number ratios to form compounds. This

Subatomic Particles - MCQ Practice Set

01. Which of the following statements regarding subatomic particles is true? a) They are larger than atoms b) They are the smallest constituents of matter c) They do not contribute to the mass of atoms d) They are not involved in chemical bonding Answer: b) They are the smallest constituents of matter Explanation: Subatomic particles are particles that are smaller than atoms and constitute the building blocks of matter, making option b the correct choice. 02. What is the electric charge of an electron? a) +1.602 x 10⁻¹⁹ coulombs b) -1.602 x 10⁻¹⁹ coulombs c) 0 coulombs d) +9.109 x 10⁻³¹ kilograms Answer: b) -1.602 x 10⁻¹⁹ coulombs Explanation: Electrons carry a negative electric charge of -1.602 x 10⁻¹⁹ coulombs. 03. What is the primary role of electrons in atoms? a) Contributing to the stability of atomic nuclei b) Determining the atomic number c) Participating in chemical bonding d) Carrying a positive electric charge Answer: c) Participating in chemical bonding Explanation: Electro

Subatomic Particles

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Subatomic particles are particles that are smaller than an atom, constituting the building blocks of atoms and forming the basis of all matter. These particles include electrons, protons and neutrons, which are the three primary subatomic particles found within atoms. These subatomic particles play crucial roles in determining the properties of atoms and molecules. Protons and neutrons contribute to the mass of the atom and are involved in nuclear reactions, while electrons are responsible for chemical bonding and the formation of chemical compounds through interactions with other atoms. Understanding the characteristics and behavior of subatomic particles is essential for comprehending the structure of matter and the behavior of atoms in various chemical and physical processes. Electron: An electron is a subatomic particle that carries a negative electric charge -1.602 × 10⁻¹⁹ coulombs and has a mass of approximately 9.109 × 10⁻³¹ kilograms. It is one of the fundamental constituents o