CBSE Class 12 Chemistry The d and f Block Elements MCQs Set 04

Question: A compound in which a metal ion M^x+ (Z = 25)has a spin only magnetic moment of ✓24 BM. The number of unpaired electrons in the compound and the oxidation state of the metal ion are respectively 
(a) 4 and 2
(b) 5 and 3
(c) 3 and 2
(d) 4 and 3
(e) 3 and 1
Answer: d

Question: Gun metal is
(a) Cu + Zn
(b) Cu + Sn + Zn
(c) Cu + Sn
(d) Zn + Sn
Answer: b

Question: The atomic numbers of vanadium (V), chromium (Cr), manganese (Mn) and iron (Fe) are respectively 23, 24, 25 and 26. Which one of these may be expected to have the highest second ionisation enthalpy ? 
(a) V
(b) Cr
(c) Mn
(d) Fe
Answer: b

Question: Stainless steel has iron and
(a) Cr
(b) Cu
(c) Co
(d) Zn
Answer: a

Question: Which of the oxide of manganese is amphoteric?
(a) MnO₂
(b) Mn₂O₃ 
(c) Mn₂O₇
(d) MnO 
Answer: a

Question: A transition metal ion exists in its highest oxidation state. It is expected to behave as
(a) a chelating agent
(b) a central metal in a coordination compound
(c) an oxidising agent
(d) a reducing agent
Answer: c

Question: When hydrogen peroxide is added to acidified potassium dichromate, a blue colour is produced due to formation of
(a) CrO₃
(b) Cr₂O₃
(c) CrO₅ 
(d) CrO₄^2-
(e) Cr₂O₇^2-
Answer: c

Question: In context with the transition elements, which of the following statement is incorrect ? 
(a) In addition to the normal oxidation state, the zero oxidation state is also shown by these elements in complexes
(b) In the highest oxidation state, the transition metal shows basic character and form cationic complexes
(c) In the highest oxidation state of the first five transition elements (Sc to Mn), all the 4s and 4d electrons are used for boncling
(d) Once the d⁵ configuration is exceeded, the tendency to involve all the 3d electrons in bonding decreases
Answer: b

Question: Transition metal ions show colour because 
(a) they absorb light
(b) they emit light
(c) they are paramagnetic
(d) they exhibit d -d transition
Answer: d

Question: Mercury is a liquid metal because
(a) it has a completely filled s-orbital
(b) it has a small atomic size
(c) it has a completely filled d-orbital that prevents d-d overlapping of orbitals
(d) it has a completely filled d-orbital that causes d-d overlapping
Answer: c

Question: The lanthanoid which exhibits + 4 oxidation 
(a) Pm
(b) Sm
(c) Ce
(d) Gd 
Answer: c

Question: The magnetic moment of a transition metal ion is √15 BM. Therefore, the number ofunpaired electrons present in it, is
(a) 3
(b) 4
(c) 1
(d) 2
Answer: a

Question: Corrosive sublimate (HgCI₂ ) can be used to distinguish between 
(a) formic acid and acetic acid
(b) acetaldehyde and butanone
(c) formaldehyde and propanone
(d) All of the above
Answer: a

Question: An ƒ-shell containing 6 unpaired electrons can exchange
(a) 6 electrons
(b) 9 electrons 
(c) 12 electrons
(d) 15 electrons 
Answer: d

Question: KMnO₄ (acidic/alkaline) is not decolourised by 
(a) Mohr salt
(b) oxalic acid
(c) benzene
(d) propene
Answer: c

Question: Which of the following compound is expected to be coloured ? 
(a) Ag₂SO₄
(b) CuF₂
(c) MgF₂
(d) CuCl 
Answer: b

Question: What is the oxidation state of iron in Mohr’s salt? 
(a) + 3
(b) 0
(c) + 2
(d) + 1
Answer: c

Question: Which of the following compounds volatilises on heating?
(a) MgCI₂
(b) HgCI₂
(c) CaCI₂
(d) FeCI₃
Answer: b

Question: Zn does not show variable valency because of
(a) complete d-subshell
(b) inert pair effect
(c) 4s²-subshell
(d) None of these 
Answer: a

Question: MnO^–₄ reacts with bromide ion in alkaline medium to give 
(a) MnBr₄
(b) MnOBr₂
(c) MnO₂, BrO^–₃
(d) MnO, BrO 
Answer: c

Question: Atomic radius of Ti, Zr and Hf vary 
(a) Ti > Zr > Hf
(b) Ti < Zr < Hf
(c) Ti < Hf < Zr
(d) Ti < Zr = HF
Answer: d

Question: The correct statement is 
(a) the earlier members of lanthanoid series resemble calcium in their chemical properties
(b) the extent of actinoid contraction is almost the same as lanthanoid contraction
(c) in general, lanthanoid and actinoids do not show variable oxidation states
(d) Ce⁴⁺ in aqueous solution is not known
Answer: a

Question: The magnetic moment of a salt containing Zn²⁺ ion is
(a) 0
(b) 1.87 
(c) 5.92
(d) 2
Answer: a

Question: Which of the following is not a member of 3d-transition series ? 
(a) Fe
(c) Au
(b) Co
(d) Cu
Answer: c

Question: Excess of KI reacts with CuSO₄ solution and then Na₂S₂O₃ solution is added to it. Which of the statements is incorrect for this reaction ? 
(a) Cu₂I₂ fonned
(b) Cul₂ is formed
(c) Na Na₂S₂O₃ is oxidised
(d) Evolved I₂ is reduced
Answer: b

Question: Cl₂ + HgO → ?
(a) Cl₂O + HgCl
(c) ClO + HgCl
(b) Cl₂O + HgCl₂
(d) ClO + HgCl₂
Answer: b

Question: When oxyhaemoglobin changes to deoxyhaemoglobin, Fe²⁺ ion changes from 
(a) diamagnetic to paramagnetic
(b) paramagnetic to diamagnetic
(c) diamagnetic to ferromagnetic
(d) paramagnetic to ferromagnetic
Answer: a

Question: The magnetic moment of a transition metal ion is 3 .87 BM. The number of unpaired electrons present in it is 
(a) 2
(b) 3
(c) 4
(d) 5
Answer: b

Question: Formation of coloured solution is possible when metal ion in the compound contains
(a) paired electrons
(b) lone pair of electrons
(c) unpaired electrons
(d) None of these
Answer: c

Question: Which of the following pairs of elements cannot form an alloy ? 
(a) Zn, Cu
(b) Fe, Hg
(c) Fe, C
(d) Hg, Na
Answer: b

Question: Pick out the correct statements from the following.
I. Cobalt (III) is more stable in octahedral complexes.
II. Zinc forms coloured ions or complexes.
III. Most of the d-block elements and their compounds are ferromagnetic.
IV. Osmium shows (VIII) oxidation state.
V. Cobalt (II) is more stable in octahedral complexes.
(a) I and II
(b) I and III
(c) II and IV
(d) I and IV
(e) II and V
Answer: d

Question: The following two reactions HNO₃ with Zn are given as (equations are not balanced)
I. Zn+ cone. HNO₃ → Zn (NO₃)₂ + X + H₂O (A)
II. Zn + di!. HNO₃ → Zn (NO₃)₂+ Y + H₂O (B)
In reactions I and II, the compounds X and Y respectively, are
(a) NO₂ and NO
(c) NO and NO₂
(b) NO₂and NO₂
(d) NO₂ and NH₄NO₃
Answer: d