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Atomic Structure covers the fundamental concepts of atoms, including subatomic particles like protons, electrons, and neutrons, atomic models, and quantum numbers.
The positively charged part at the center of an atom is called as :
Correct Answer:
(D)
Nucleus
The positively charged part at the centre of an atom is called as nucleus. The atomic nucleus is the small, dense region consisting of proton and neutron at the centre of an atom.
Ques: 2
Which of the following is not a part of an atom?
Correct Answer:
(D)
Photon
Proton, electron and neutron are part of an atom, but the photon is associated with light energy and also known as energy packet of light.
Ques: 3
A single type of atom is found in –
Correct Answer:
(C) Native elements
Native element is a material that consists of a single type of atom, while a compound consists of two or more types of atoms.
Ques: 4
The atomic nucleus was discovered by :
Correct Answer:
(A) Rutherford
The nucleus is a very dense region consisting of protons and neutrons at the centre of an atom. It was discovered in 1911 as a result of Ernest Rutherford’s interpretation of the 1909 Geiger–Marsden gold foil experiment. The proton–neutron model of the nucleus was proposed by Dmitri Ivanenko in 1932.
Ques: 5
In atom, neutron was discovered by :
Correct Answer:
(B) Chadwick
Neutron is a neutral particle which has no electrical charge. It was discovered by Chadwick in 1932. He discovered that when Beryllium (Be) or other atoms are bombarded with high speed particles, then electrically neutral particles emerges from these atoms and such neutral particles are known as neutrons.
Ques: 6
Which one of the following pairs constitutes particle- antiparticle pair?
Correct Answer:
(A) Electron - Positron
The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. The positron has a positive electric charge and has the same mass as an electron.
Ques: 7
Match List-I with List-II and select the correct answer using the codes given below the lists :
List-I (Characteristic) List-II (Particle)
A. Zero mass 1. Positron
B. Fractional charge 2. Neutrino
C. Fractional spin 3. Quark
D. Integral spin 4. Phonon
Code :
A B C D
Correct Answer:
(A) 2 3 1 4
The positron has a positive electric charge (+1e) and has the same mass and a spin of 1/2 as an electron. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons and are the components of atomic nuclei. They have fractional charge of +2/3e or -1/3e. Neutrinos are sub-atomic particles produced by the decay of radioactive elements and are elementary particles that lack an electric charge and a very small mass, which might even be zero. Phonon, in condensed-matter physics, a unit of vibrational energy that arises from oscillating atoms within a crystal. A phonon is a definite discrete unit or quantum of vibrational mechanical energy, just as a photon is a quantum of electromagnetic or light energy. Phonon has integral spin like photon.
Ques: 8
Which one is a fundamental particle?
Correct Answer:
(D)
Quark
In particle physics, an elementary particle or fundamental particle is a subatomic particle with no sub-structure, thus not composed of other particles. Particles currently thought to be elementary include the fundamental fermions (quarks, leptons, antiquarks and antileptons) as well as fundamental bosons.
Ques: 9
Higgs Boson are also known as :
Correct Answer:
(D)
God Particles
The Higgs Boson is the fundamental particle associated with the Higgs field, a field that gives mass to other fundamental particles such as electrons and quarks. In the mainstream media, the Higgs boson has often been called the 'God Particle' from the 1993 book 'The God Particle' by Nobel Laureate Leon Lederman.
Ques: 10
A pure substance which contains only one type of atom is called:
Correct Answer:
(A) Element
A pure substance which contains only one type of atoms is an element.An element contains only one type of atoms. It cannot be broken down or transformed into a simpler substance. Elements combine chemically in fixed proportions to form another type of a pure substance called a compound. Examples of elements are oxygen (O), fluorine (F) etc. Examples of compounds are water (H2O), sodium chloride (NaCl) etc.
Ques: 11
Who proposed the plum pudding model of an atom:
Correct Answer:
(A) J.J. Thomson
: The "plum pudding model" of the atom was proposed by J.J. Thomson after he discovered the electron. The model envisioned the atom as a sphere of positively charged "pudding" with negatively charged electrons embedded within it, similar to how plums are scattered in a pudding.
Ques: 12
Which particle is free of charge?
Correct Answer:
(C) Neutron
Among the given particles neutron is free of charge. α (alpha) particle (+2ve) and proton (+ve) are positive charged particles while electron (–ve) carries negative charge.
Ques: 13
Which of the following particles has zero charge?
Correct Answer:
(B) Neutrino
A neutrino is a subatomic particle that is very similar to an electron, but has no electrical charge and a very small mass, which might even be zero. Neutrinos are one of the most abundant particles in the universe. Because they have very little interaction with matter, however, they are incredibly difficult to detect.
Ques: 14
The alpha particle carries two positive charges. Its mass is very nearly equal to that of –
Correct Answer:
(B) Nucleus of an atom of helium
An alpha particle is a fast moving particle containing two protons and two neutrons (a helium nucleus). Its mass is equal to that of helium atom's nucleus. Alpha particles carry a charge of +2 and strongly interact with matter. Produced during alpha decay, alpha particles can travel only a few inches through the air and can be easily stopped with a sheet of paper.
Ques: 15
Which of the following elements does not contain neutrons?
Correct Answer:
(C) Hydrogen
The atomic no. of Hydrogen is 1. The Protium (1H1) isotope of the Hydrogen has no neutron while Deuterium (1H2) has one neutron and Tritium (1H3) isotope has 2 neutrons.
Ques: 16
Which of the following carries a negative charge?
Correct Answer:
(C) Beta particles
Alpha rays or Alpha particles (α) are the positively charged particles. Beta particles (β) are highly energetic electrons which are released from inner part of a nucleus. They are negatively charged (-1e) and have a negligible mass. Gamma radiation (γ) consist of photons, which travel at the speed of light like all electromagnetic radiations. A ray has no mass or charge. Gamma radiation can travel much faster (speed of light) in the air than alpha and beta.
Ques: 17
In an atom, the order of filling up of the orbitals is governed by –
Correct Answer:
(A) Aufbau's principle
The Aufbau principle is used to determine the electron configuration of an atom, molecule or ion. The principle postulates a hypothetical process in which an atom is 'built up' by progressively adding electrons. As they are added, they assume their most stable condition (electron orbitals) with respect to the nucleus and those electrons already there. According to the principle, electrons fill orbitals starting at the lowest available (possible) energy levels before filling higher levels (e.g. 1s before 2s).
Ques: 18
The number of electrons and neutrons in an element is 18 and 20 respectively. Its mass number is
Correct Answer:
(C) 38
Given that,
number of neutrons = 20 & number of electrons = 18
Thus, number of protons = number of electrons = 18
Mass number = number of protons + number of neutrons = 18 + 20 = 38
Ques: 19
What is the mass number of an element, the atom of which contains two protons, two neutrons and two electrons?
Correct Answer:
(B) 4
The mass number of an element is the sum of a total number of protons and neutrons inside in its nucleus and represents by A. Therefore, mass number A= number of protons + number of neutrons. Therefore, mass number = 2 + 2 = 4
Ques: 20
The atoms, in which the number of protons is same but the number of neutrons is different, are known as –
Correct Answer:
(D)
Isotopes
The Isotopes are a set of nuclides/atoms having the same number of protons, but a different number of neutrons. In other words, the same atomic number but having different atomic mass. Each individual isotope has a separate nuclei. The Isotopes that are unstable and undergo radioactive decay are called radioisotopes.