Chemistry Chapter 2 Entry Test MCQs
101. The number of electrons that can be accommodated in 5f sub shell is:
a. 50
b. 14
c. 2
d. 7
Electronic Configuration
102. Electronic configuration of an atom is 1s2, 2s2,2p4. Number of unpaired electrons are
a. 3
b. 1
c. 4
d. 2
103. The ground state electronic configuration of the element which is iso-electronic which H2O
a. 1s2, 2s2, 2p6
b. 1s2, 2s2, 2p6, 3s2,3p4
c. 1s2, 2s2, 2p6, 3s2
d. 1s2, 2s2, 2p6, 3s2
104. Gaseous metal ion M2+ has 5 unpaired electrons. What is its atomic number?
a. 27
b. 25
c. 28
d. 26
105. The electronic configuration 1s2, 2s2, 2p6, 3s1, 3p1 is correctly described by
a. The excited state of Na+
b. The excited state of Mg+
c. The excited state of Al
d. The excited state of Mg
106. The orbital diagram in which the Auf bau principle is violated is
107. Which order of energies of orbitals is correct in a many electron atom?
a. 4s > 5s
b. 3d < 2s
c. 3s < 3p
d. 2s = 2p
108. Which of the following represent electronic configuration violate the Auf bau principle? I. [Ne] 3s1 3p5 II. [Kr] 4d10 5s2 5p3 III. [Ar] 3d10 4s2 4p2
a. Only (II)
b. Only (I)
c. Both (I) and (III)
d. Both (II) and (III)
109. The number of d-electrons in Ni (atomic number = 28) is equal to that of the
a. Total electrons in N (atomic number = 7)
b. d-electrons in Ni2+
c. p-electrons in Ar (atomic number = 18)
d. s and p-electrons in F–
110. Which of the following electronic configuration does not follow the Pauli’s exclusion principle?
a. 1s2 2s2
b. 1s2 2s2 2p4
c. 1s2 2s2 2p6 3s3
d. 1s2 2s2 2p6 3s2
111. The number of d-electrons retained in Fe? (At. number of Fe = 26) ions is
a. 5
b. 3
c. 6
d. 4
112. The orbital diagram in which the Pauli’s exclusion principle is violated is:
113. Which electronic configuration is not possible?
a. 1s2
b. 1s2, 2s2, 2p6, 2d2, 3s1
c. 1s2, 2s2, 2p6
d. 1s1, 2s2, 2p1x, 2p1y, 2p1z
114. How many total unpaired electrons are present in an atom with Z = 24
a. 6
b. 2
c. 8
d. 5
115. When 4f orbital is complete the entering electron goes into
a. 5d
b. 6s
c. 4d
d. 5p
116. Without applying Hund’s rule, the electronic configuration of one of the following cannot be justified
a. Na
b. F
c. P
d. Ne
117. If both the K and L shells are full, what would be the atomic number of that element?
a. 10
b. 20
c. 16
d. 14
118. Which one of the following electronic configurations represents an element that forms a simple ion with a charge of -3?
a. 1𝑠2 2𝑠2 2𝑝6 3𝑠2 3𝑝3
b. 1𝑠2 2𝑠2 2𝑝6 3𝑠2 3𝑝1
c. 1𝑠2 2𝑠2 2𝑝6 3𝑠2 3𝑝6 3𝑑3 4𝑠2
d. 1𝑠2 2𝑠2 2𝑝6 3𝑠2 3𝑝6 3𝑑1 4𝑠
119. Which of the following particles would, on losing an electron, have a half-filled set of p orbitals?
a. N
b. 𝐶−
c. 𝑂+
d. 𝑁−
120. The order of subshells in a shell with respect to the relative energies
a. s > f > p > d
b. s > p > d > f
c. s < p < f < d
d. s < p < d < f
121. Which of the following is correct with respect to the application of principle?
a. Auf-bau principle = electrons in orbital
b. Hund’s rule = electron in subshells
c. n + l = electrons in orbitals
d. Pauli’s principle = spin of electrons in one orbital
122. The electronic configuration of an element in monovalent state is [18Ar], 4s2, 3d4. This electronic configuration of represents an element
a. Mn
b. Cr
c. Co
d. Al
123. In chromium (Cr – 24) the number of electrons with azimuthal quantum numbers, l = 1 and 2 are respectively:
a. 12 and 5
b. 12 and 4
c. 16 and 5
d. 16 and 4
124. Which of the following statements is incorrect about isolated, gaseous atoms?
a. For any atom, the three 2p atomic orbitals are degenerate
b. For an O atom, the energy of the 1s atomic orbital is lower than that of the 2s atomic orbital
c. For an H atom, 3s atomic orbital and 2p atomic orbital are equal in energy due to same n+l
d. For a C atom, the energies of the 2s and 2p atomic orbitals are different
125. Number of unpaired electrons in N2+
a. 2
b. 3
c. 0
d. 1