Atomic structure

21.Who was the discoverer of neutrons?
 
A. Ernest Rutherford
 
B. J. J. Thomson
 
C. James Chadwick
 
D. None of the above
 
Option “C” is correct.
James Chadwick discovered a neutral particle and named it neutron. Thus the neutrons were discovered by James Chadwick.
22.Meson was discovered by:
 
A. Yukawa
 
B. Austin
 
C. Moseley
 
D. Einstein
 
Option “A” is correct.
Meson was discovered by Yukawa. They are a hadron particle because they consist of quarks.
23.Which one of the following is the correct electronic configuration of chlorine?
 
A. 2,7,8
 
B. 2,8,7
 
C. 2,8,8
 
D. 7,8,9
 
Option “B” is correct.
Chlorine has atomic number 17. Its electronic configuration is 2, 8, 7. It is the second-lightest of the halogens, it appears between fluorine and bromine in the periodic table.
24.Rutherford’s α particles were the first to show that atoms contain
 
A. electron
 
B. Proton
 
C. nucleus
 
D. neutrons
 
Option “C” is correct.
Rutherford’s experiment on scattering of α-particles showed for the first time that the atom has nucleus. He observed that the positively charged α-particles were repelled and deflected by the positive charges in the atom. Rutherford’s named this positively charged portion of atom as nucleus.
25.The orientation of an atomic orbital is governed by:
 
A. Azimuth quantum number
 
B. Spin quantum number
 
C. Magnetic quantum number
 
D. Principal quantum number
 
Option “C” is correct.

Quantum mechanical model has been derived from Schrodinger’s Equation
Three of the quantum numbers have been derived from this equation.
These are: Principal quantum number, Azimuthal quantum number, and Magnetic quantum number
The spin quantum number is the only one that has not been derived from the equation.
1. Principle Quantum Number:
It is denoted by n. It gives information about the shell number of the electron. In the periodic table, it gives information about the periods.

2. Azimuthal Quantum Number:
It is denoted by l. It gives information about the sub-shell. Sub-shells represent the lines obtained in atomic spectrums. In the periodic table, it gives information about groups.

3. Magnetic Quantum Number:
It is denoted by m. It gives information about the orientation of the different orbitals that are present in the sub-shells. They were discovered from fine lines present on the atomic spectrum. In the periodic table, it gives information about the groups.

4. Spin Quantum Number:
It is denoted by s. It represents spins of electrons. No two-electron with the same spin can occupy the same orbital.

Hence, the orientation of an atomic orbital is governed by magnetic quantum numbers.

26.The three basic components of an atom are-
 
A. protons, neutrons and ions
 
B. protons, neutrons and electrons
 
C. Protium, Deuterium and Tritium
 
D. protons, neutrinos and ions
 
Option “B” is correct.
The three basic components of an atom are Protons, Neutrons & Electrons.
The Protons, Neutrons & Electrons have the Positive, Neutral & Negative Charges respectively.
The Fundamental particles of atoms also consist of subatomic particles which include nucleons and quarks.
The number of protons in an atom does not change, fewer or extra electrons can create a special atom called an ion.
27.The nucleus of a singly ionized carbon atom contains ________.
 
A. 6 protons, 6 neutrons
 
B. 5 protons, 6 neutrons
 
C. 6 protons, 6 neutrons, 6 electrons
 
D. 12 protons, 6 neutrons, 6 electrons
 
Option “A” is correct.
The charged carbon atom in a carbocation is a “sextet”. i.e., it has only six electrons in its outer valence shell instead of the eight valence electrons that ensures maximum stability (octet rule). Therefore carbocations are often reactive, seeking to fill the octet of valence electrons as well as regain a neutral charge.
28.Which of the following is not a part of nucleus?
 
A. Nuclear Membrane
 
B. Nucleolus
 
C. Endosomes
 
D. Photon
 
Option”D” is correct.
29.When there are two electrons in the same orbital, they have _______.
 
A. same spins
 
B. opposite spins
 
C. different energies
 
D. parallel spin
 
Option “B” is correct.
30.Who among the following proposed that atom is prime?
 
A. Dalton
 
B. Bergilius
 
C. Rutherford
 
D. Avogadro
 
Option “A” is correct.
John Dalton proposed the theory that atom is indivisible. He considered atom to be the smallest part of matter and which cannot be further divided.

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