NEET d and f block elements Previous year Questions with Answer key

1. Sc (Z = 21) is a transition element but Zn (Z = 30) is not because element b (NEET 2013)

(a) both Sc³⁺ and Zn²⁺ ions are colourless and form white compounds

(b) in case of Sc, 3d orbitals are partially filled but in Zn these are filled

(d) both Sc and Zn do not exhibit variable oxidation states

2. Which of the following ions has electronic configuration [Ar]3d⁶? (2010)

(a) Ni³⁺ (b) Mn³⁺ (c) Fe³⁺ (d) Co³⁺

8. Identify the incorrect statement. (NEET 2020)

(a) Cr²⁺ (d⁴) is a stronger reducing agent than Fe²⁺ (d⁶) in water.

(b) The transition metals and their compounds are known for their catalytic activity due to their ability to adopt multiple oxidation states and to form complexes.

(c) Interstitial compounds are those that are formed when small atoms like H, C or N are trapped inside the crystal lattices of metals.

8. Identify the incorrect statement. (NEET 2020)

(a) Cr²⁺ (d⁴) is a stronger reducing agent than Fe²⁺ (d⁶) in water.

(b) The transition metals and their compounds are known for their catalytic activity due to their ability to adopt multiple oxidation states and to form complexes.

(c) Interstitial compounds are those that are formed when small atoms like H, C or N are trapped inside the crystal lattices of metals.

(d) The oxidation states of chromium in CrO₄^2– and Cr₂O₇^2– are not the same.

9. The calculated spin only magnetic moment of Cr²⁺ ion is (NEET 2020)

(a) 3.87 BM (b) 4.90 BM

10.

(a) A – (iv) B – (v) C – (ii) D – (i)

(b) A – (i) B – (ii) C – (iii) D – (iv)

(d) A – (iii) B – (v) C – (i) D – (ii)

11. Magnetic moment 2.84 B.M. is given by (At. nos. Ni = 28, Ti = 22, Cr = 24, Co = 27) (2015)

(a) Cr²⁺ (b) Co²⁺ (c) Ni²⁺ (d) Ti³⁺

12. Which of the following processes does not involve oxidation of iron? (2015)

(a) Formation of Fe(CO)₅ from Fe.

(b) Liberation of H₂ from steam by iron at high temperature.

(d) Decolourisation of blue CuSO₄ solution by iron.

13. Which of the following statements about the interstitial compounds is incorrect? (NEET 2013)

(a) They are much harder than the pure metal.

(b) They have higher melting points than the pure metal.

(d) They are chemically reactive.

14. Identify the alloy containing a non-metal as a constituent in it. (2012)

(a) Invar (b) Steel

15. The catalytic activity of transition metals and their compounds is ascribed mainly to (Mains 2012)

(a) their magnetic behaviour

(b) their unfilled d-orbitals

(d) their chemical reactivity.

16. Which one of the following does not correctly represent the correct order of the property indicated against it? (Mains 2012)

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

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

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

17. Four successive members of the first series of the transition metals are listed below. For which one of them the standard potential (E°_M2+/M) value has a positive sign? (Mains 2012)

(a) Co (Z = 27) (b) Ni (Z = 28)

18. 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? (2011)

(a) Mn > Fe > Cr > Co (b) Fe > Mn > Co > Cr

(At. nos. Cr = 24, Mn = 25, Fe = 26, Co = 27)

19. Which of the following ions will exhibit colour in aqueous solutions? (2010)

(a) La³⁺ (Z = 57) (b) Ti³⁺ (Z = 22)

20. Which of the following pairs has the same size? (2010)

(a) Fe²⁺, Ni²⁺ (b) Zr⁴⁺, Ti⁴⁺

21. Which one of the elements with the following outer orbital configurations may exhibit the largest number of oxidation states? (2009)

(a) 3d⁵4s¹ (b) 3d⁵4s²

22. The correct order of decreasing second ionisation enthalpy of Ti(22), V(23), Cr(24) and Mn(25) is (2008)

(a) Mn > Cr > Ti > V (b) Ti > V > Cr > Mn

23. In which of the following pairs are both the ions coloured in aqueous solution?

(At. no. : Sc = 21, Ti = 22, Ni = 28, Cu = 29,Co = 27) (2006)

(a) Ni²⁺, Cu⁺ (b) Ni²⁺, Ti³⁺

24. 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 ionisation enthalpy? (2005)

(a) Vanadium (Z = 23)

(b) Chromium (Z = 24)

(d) Iron (Z = 26)

25. The aqueous solution containing which one of the following ions will be colourless? (2005)

(Atomic number : Sc = 21, Fe = 26,Ti = 22, Mn = 25)

(a) Sc³⁺ (b) Fe²⁺

36. The manganate and permanganate ions are tetrahedral, due to (NEET 2019)

(a) the π-bonding involves overlap of d-orbitals of oxygen with d-orbitals of manganese

(b) the π -bonding involves overlap of p-orbitals of oxygen with d-orbitals of manganese

(d) the π -bonding involves overlap of p-orbitals of oxygen with p-orbitals of manganese.

37. When neutral or faintly alkaline KMnO4 is treated with potassium iodide, iodide ion is converted into ‘X’. ‘X’ is (NEET 2019)

(a) I₂ (b) IO₄^– (c) IO₃^– (d) IO^–

38. Which one of the following ions exhibits d-d transition and paramagnetism as well? (NEET 2018)

(a) CrO₄^2– (b) Cr₂O₇^2-