CBSE Class 12 Chemistry The d and f Block Elements MCQs Set B

Question : The number of unpaired electrons in a nickel atom in ground state are (At. No. of Ni = 28)

(a) 2 

(b) 5

(c) 3

(d) 7

Answer : A

Question : Which one of the following is an example of non-typical transition elements ?

(a) Li, K, Na 

(b) Be, Al, Pb

(c) Zn, Cd, Hg 

(d) Ba, Ga, Sr.

Answer : C

Question : Which of the following has the maximum number of unpaired electrons?

(a) Ti2+ 

(b) Fe2+

(c) Cr+ 

(d) Cu+

Answer : C

Question : The outer electronic configuration of Ag is 4d ¹⁰ 5s¹, it belongs to

(a) 5th period, group 4 

(b) 4th period, group 5

(c) 5th period, group 11 

(d) 6th period, group 9

Answer : C

Question : Manganese belongs to

(a) 1st transition series

(b) 2nd transition series

(c) 3rd transition series 

(d) 4th transition series

Answer : A

Question : The no. of unpaired electrons in Mn⁷⁺ ions (At. no. of Mn = 25) is

(a) 0 

(b) 1

(c) 2 

(d) 3

Answer : A

Question : Which one of the following species is paramagnetic?

(a) N2 

(b) Co

(c) Cu+ 

(d) Zn

Answer : B

Question : Which of the following species is/are paramagnetic?

Fe²⁺, Zn0, Hg²⁺, Ti⁴⁺

(a) Fe²⁺ only 

(b) Zn0 and Ti⁴⁺

(c) Fe²⁺ and Hg²⁺ 

(d) Zn0 and Hg²⁺

Answer : A

Question : In first transition series, the melting point of Mn is low because

(a) due to d¹⁰ configuration, metallic bonds are strong

(b) due to d⁷ configuration, metallic bonds are weak

(c) due to d⁵ configuration, metallic bonds are weak

(d) None of these

Answer : C

Question : The transition metals have a less tendency to form ions due to

(a) high ionisation energy

(b) low heat of hydration of ions

(c) high heat of sublimation

(d) All of these

Answer : D

Question : The common oxidation states of Ti are

(a) + 2 and + 3 

(b) + 3 and + 4

(c) – 3 and – 4 

(d) + 2, + 3 and + 4

Answer : D

Question : Maximum oxidation state is shown by

(a) Os 

(b) Mn

(c) Co 

(d) Cr

Answer : A

Question : Which one of the elements with the following outer orbital configurations may exhibit the largest number of oxidation states?

(a) 3d⁵4s¹ 

(b) 3d⁵4s²

(c) 3d²4s² (d) 3d³4s²

Answer : B

Question : Which of the following pairs has the same size?

(a) Fe²⁺ , Ni²⁺ 

(b) Zr⁴⁺ , Ti⁴⁺

(c) Zr⁴⁺ , Hf ⁴⁺ 

(d) Zn2+ , Hf ⁴⁺

Answer : C

Question : For the four successive transition elements (Cr, Mn, Fe and Co), the stability of +2 oxidation state will be there in which of the following order?

(a) Mn > Fe > Cr > Co 

(b) Fe > Mn > Co > Cr

(c) Co > Mn > Fe > Cr 

(d) Cr > Mn > Co > Fe

Answer : A

Question : Iron exhibits +2 and + 3 oxidation states. Which of the following statements about iron is incorrect ?

(a) Ferrous oxide is more basic in nature than the ferric oxide.

(b) Ferrous compounds are relatively more ionic than the corresponding ferric compounds.

(c) Ferrous compounds are less volatile than the corresponding ferric compounds.

(d) Ferrous compounds are more easily hydrolysed than the corresponding ferric compounds.

Answer : D

Question : Four successive members of the first row transition elements are listed below with their atomic numbers. Which one of them is expected to have the highest third ionization enthalpy?

(a) Vanadium (Z = 23) 

(b) Chromium (Z = 24)

(c) Manganese (Z = 25) 

(d) Iron (Z = 26)

Answer : C

Question : Of the following outer electronic configurations of atoms, the highest oxidation state is achieved by which one of them ?

(a) (n – 1)d³ ns² 

(b) (n – 1)d⁵ ns¹

(c) (n – 1)d⁸ ns² 

(d) (n – 1)d⁵ ns²

Answer : D

Question : For d block elements the first ionization potential is of the order

(a) Zn > Fe > Cu > Cr 

(b) Sc = Ti < V = Cr

(c) Zn < Cu < Ni < Co 

(d) V > Cr > Mn > Fe

Answer : A

Question : Which of the following does not represent the correct order of the properties indicated ?

(a) Ni²⁺ > Cr²⁺ > Fe²⁺ > Mn²⁺ (size)

(b) Sc > Ti > Cr > Mn (size)

(c) Mn²⁺ > Ni²⁺ < Co²⁺ 2+ (unpaired electron)

(d) Fe²⁺ > Co²⁺ > Ni²⁺ > Cu²⁺ (unpaired electron)

Answer : A

Question : Zinc and mercury do not show variable valency like d-block elements because

(a) they are soft

(b) their d-shells are complete

(c) they have only two electrons in the outermost subshell

(d) their d-shells are incomplete

Answer : B

Question : Which of the following transition element shows the highest oxidation state ?

(a) Mn 

(b) Fe

(c) V 

(d) Cr

Answer : A

Question : Which of the following elements does not showvariable oxidation states?

(a) Copper 

(b) Iron

(c) Zinc 

(d) Titanium

Answer : C

Question : Which one of the following transition elements does not exhibit variable oxidation state?

(a) Ni 

(b) Cu

(c) Fe 

(d) Sc

Answer : D

Question : Electronic configuration of a transition element X in +3 oxidation state is [Ar]3d⁵. What is its atomic number ?

(a) 25 

(b) 26

(c) 27 

(d) 24

Answer : B

Question : Metallic radii of some transition elements are given below. Which of these elements will have highest density ?

Element Fe Co Ni Cu

Metallic radii/pm 126 125 125 128

(a) Fe 

(b) Ni

(c) Co 

(d) Cu

Answer : D

Question : Transition metals mostly are

(a) diamagnetic

(b) paramagnetic

(c) neither diamagnetic nor paramagnetic

(d) both diamagnetic and paramagnetic

Answer : B

Question : Transition metals usually exhibit highest oxidation states in their

(a) chlorides 

(b) fluorides

(c) bromides 

(d) iodides

Answer : B

Question : Which of the following statements is incorrect?

(a) Zn,Cd and Hg due to presence of completely filled d-orbitals [(n–1)d¹⁰ns²] are not studied along with other transition metals.

(b) Zn, Cd and Hg have low m.p and are comparitively softer than other transition metals.

(c) Metallic bond made by elements with d ⁵ configuration is stronger as compared to metalic bond made by elements with d ³ configuration.

(d) Metals of 5^d series forms strong metallic bonds as compared with metals of 3^d series.

Answer : A

Question : Which of the following is incorrect?

(a) Mn shows oxidation state of +7 in MnF₇

(b) Fe and Co shows +3 oxidation state in FeX₃ and CoF₃.

(c) V shows oxidation state of + 5 in VF₅.

(d) Cu does not shows +2 oxidation state with I–.

Answer : A

Question : Which of the following is not correct about transition metals?

(a) Their melting and boiling points are high

(b) Their compounds are generally coloured

(c) They can form ionic or covalent compounds

(d) They do not exhibit variable valency

Answer : D

Question : Transition elements

(a) have low melting point

(b) exhibit variable oxidation states

(c) do not form coloured ions

(d) show inert pair effect

Answer : B

Question : Which one of the following ions is the most stable in aqueous solution?

(a) V³⁺ 

(b) Ti³⁺

(c) Mn³⁺ 

(d) Cr³⁺

(At.No. Ti = 22, V = 23, Cr = 24, Mn = 25)

Answer : D

Question : Which one of the following does not correctly represent the correct order of the property indicated against it?

(a) Ti < V < Cr < Mn : increasing number of oxidation states

(b) Ti³⁺ < V³⁺ < Cr³⁺ < Mn³⁺ : increasing magnetic moment

(c) Ti < V < Cr < Mn : increasing melting points

(d) Ti < V < Mn < Cr : increasing 2nd ionization enthalpy

Answer : C