MCQs on Class 11 Chemistry Chapter 3 Classification of Elements and Periodicity

Questions
1 Choose the correct order of atomic radii of fluorine and neon (in pm) out of the options given below and justify your answer.
A 72, 160
B 160, 160
C 72, 72
D 160, 72

Answer:72, 160
2 An element belongs to the 3rd period and group-13 of the periodic table. Which of the following properties will be shown by the element?
A Good conductor of electricity
B Liquid, metallic
C Solid, metallic
D Solid, non-metallic

Answer: A, C

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3 Ionic radii vary in
A inverse proportion to the effective nuclear charge.
B inverse proportion to the square of effective nuclear charge.
C direct proportion to the screening effect.
D direct proportion to the square of screening effect.

Answer:A, C
4 Which of the following have no unit?
A Electronegativity
B Electron gain enthalpy
C Ionisation enthalpy
D Metallic character

Answer:A, D
5 In which of the following options order of arrangement does not agree with the variation of property indicated against it?
A Al3+ < Mg2+ < Na+ < F– (increasing ionic size)
B B < C < N < O (increasing first ionisation enthalpy)
C I < Br < Cl < F (increasing electron gain enthalpy)
D Li < Na < K < Rb (increasing metallic radius)

Answer: B, C
6 Which of the following sets contain only isoelectronic ions?
A Zn2+, Ca2+, Ga3+, Al3+
B K+, Ca2+, Sc3+, Cl–
C P3-, S2-, Cl–, K+
D Ti 4+, Ar, Cr3+, V5+

Answer: B, C
7 Which of the following statements are correct?
A Helium has the highest first ionisation enthalpy in the periodic table.
B Chlorine has less negative electron gain enthalpy than fluorine.
C Mercury and bromine are liquids at room temperature.
D In any period, the atomic radius of alkali metal is the highest.

Answer:A, C, D
8 Which of the following elements will gain one electron more readily in comparison to other elements of their group?
A S (g)
B Na (g)
C O (g)
D Cl (g)

Answer:A, D
9 Which of the following sequences contain atomic numbers of only representative elements?
A 3, 33, 53, 87
B 2, 10, 22, 36
C 7, 17, 25, 37, 48
D 9, 35, 51, 88

Answer:A, D
10 Those elements impart colour to the flame on heating in it, the atoms of which require low energy for the ionisation (i.e., absorb energy in the visible region of the spectrum). The elements of which of the following groups will impart colour to the flame?
A 2
B 13
C 1
D 17

Answer:A, C
11 Which of the following elements can show covalency greater than 4?
A Be
B P
C S
D B

Answer:B, C
12 Electronic configurations of four elements A, B, C and D are given below :

(A) 1s2 2s2 2p6

(B) 1s2 2s2 2p4

(C) 1s2 2s2 2p6 3s1

(D) 1s2 2s2 2p5

Which of the following is the correct order of increasing tendency to gain electron :

A A < C < B < D
B A < B < C < D
C D < B < C < A
D D < A < B < C

Answer:A < C < B < D
13 Which of the following is the correct order of the size of the given species:
A I > I–> I+
B I+> I–> I
C I > I+> I-
D I–> I > I+

Answer:I–> I > I+
14 The elements in which electrons are progressively filled in 4f-orbital are called
A actinoids
B transition elements
C lanthanoids
D halogens

Answer:lanthanoids
15 The period number in the long form of the periodic table is equal to
A magnetic quantum number of any element of the period.
B an atomic number of any element of the period.
C maximum Principal quantum number of any element of the period.
D maximum Azimuthal quantum number of any element of the period.

Answer:maximum Principal quantum number of any element of the period.
16 Among halogens, the correct order of the amount of energy released in electron gain (electron gain enthalpy) is:
A F > Cl > Br > I
B F < Cl < Br < I
C F < Cl > Br > I
D F < Cl < Br < I

Answer:F < Cl > Br > I
17 The statement that is not correct for periodic classification of elements is:
A The properties of elements are periodic function of their atomic numbers.
B Non-metallic elements are less in number than metallic elements.
C For transition elements, the 3d-orbitals are filled with electrons after 3p-orbitals and before 4s-orbitals.
D The first ionisation enthalpies of elements generally increase with

Answer:For transition elements, the 3d-orbitals are filled with electrons after 3p-orbitals and before 4s-orbitals.
18 The electronic configuration of gadolinium (Atomic number 64) is
A [Xe] 4f 3 5d5 6s2
B [Xe] 4f7 5d2 6s1
C [Xe] 4f7 5d1 6s2
D [Xe] 4f8 5d6 6s2

Answer:[Xe] 4f7 5d1 6s2
19 The first ionisation enthalpies of Na, Mg, Al and Si are in the order:
A Na < Mg > Al < Si
B Na > Mg > Al > Si
C Na < Mg < Al < Si
D Na > Mg > Al < Si

Answer:Na < Mg > Al < Si
20 The order of screening effect of electrons of s, p, d and f orbitals of a given shell of an atom on its outer shell electrons is:
A s > p > d > f
B f > d > p > s
C p < d < s > f
D f > p > s > d

Answer: s > p > d > f

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