Short & Long Answer Questions: The d & f-Block Elements - 1 | Chemistry Class 12 - NEET PDF Download

Q.1 What are transition metals. Why are they called so?

Answer: The transition elements are those elements which have incomplete d-orbital in their ground state or common oxidation state. They are so called because they are in between s and p block elements,  
Q.2 Zn, Cd and Hg are not regarded as transition metals. Why?

Answer: In the electronic configuration of Zn, Cd and Hg the d-orbitals are completely filled in the ground state as well as in their common oxidation state. So, they are not regarded as transition metals.
Q.3 What is the lowest common oxidation state of transition metals?

Answer: Lowest common oxidation state of transition metals is +2.
Q.4 In which compound transition metals show very low oxidation states?

Answer: Compounds having ligand capable of acceptor character in addition to the bonding e.g. CO, NO, etc. show very low oxidation state.
Q.5 Define diamagnetism and par magnetism.

Answer: Substances which are attracted by applied magnetic field are called paramagnetic substances and this property is called paramagnetism while, substances which are repelled by applied magnetic field are called diamagnetic substances and this property is called diamagnetism.
Q.6 What is ferromagnetic substance? Give one example.

Answer: A substance which is attracted very strongly by applied magnetic field is called ferromagnetic substance e.g. Iron, Cobalt, nickel, etc.
Q.7 Which catalyst is used in Haber's process?

Answer: Finely divided iron is used as catalyst in Haber's process.
Q.8  In which reaction Ni is used as a catalyst?

Answer: Ni is used as catalyst in catalytic hydrogenation,
Q.9 What are interstitial compounds?

Answer: Interstitial compounds are those compounds which are formed when small atoms like H, C and N are trapped in the crystal lattice of metals.
Q.10 Name the catalyst which catalyses reaction between iodide and per sulphate ions.

Answer: Iron (III) acts as catalyst in the reaction between iodide  and persulphate ions.
Q.11 What is an alloy ?
Answer: An alloy is a homogeneous mixture of two or more metals. e.g. Brass (Cu-Zn)
Q.12 Name an alloy of transition metals with non-transition metals. 

Answer: (i) Bronze (copper-tin)
Q.13 Which transition metal of 3d series exhibits the largest number of oxidation states and why?

Answer: Manganese: It has maximum number of unpaired electron.
Q.14 What are inner transition metals ?

Answer: Those elements in which last electron goes in -orbital are called inner transition metal.
Q.15 What are lanthanoids?

Answer: Those -block elements whose last electron goes in 4subshell are called lanthanoids.
Q.16 What are actinoids?

Answer: Those -block elements whose last electron goes in 5 sub-shell are called actinoids.
Q.17 How many orbitals are incomplete in inner transition elements?

Answer: Three orbitals are incomplete in inner transition metals.
Q.18 What is lanthanoid contraction?

Answer: The gradual decrease in atomic radii or ionic radii from lanthanum to lutetium is called lanthanoid contraction.
Q.19 The radii of transition metals of 2nd series and 3rd series are very similar why?

Answer: Due to lanthanoid contraction they have same charge ratio.
Q.20 Atomic radii of Zr (160 pm) are identical with the radii of Hf (159 pm) Why?

Answer: Due to lanthanoid contraction.
Q.21 Zr and Hf occur in nature together why?

Answer: The almost similar atomic radii of zirconium and hafnium as a consequence of lanthanoid contraction account for their occurrence together.
Q.22 Separation of Zr and Hf from a mixture is difficult. Explain

Answer: Due to their similar atomic radii they have common physical properties due to which their separation is difficult.
Q.23 Name the lanthanoids which show very low value of third ionisation enthalpy.

Answer: Europium (Eu).
Q.24 What is mischmetal?

Answer: Mischmetal is an alloy of 95% lanthanoids and 5% iron with the traces of S, C, Ca and Al.
Q.25 What are the uses of mischmetal?

Answer: Mischmetal is used to produce bullets, shells and light flint.
Q.26 Which compound is used as phosphors in T.V. screens?

Answer: Lanthanoid oxide.
Q.27 Give one use of mixed oxides of lanthanoids.

Answer: Mixed oxides of lanthanoids are employed as catalysts  petroleum cracking.
Q.28 What is the most common oxidation state shown by actinoids?

Answer: is most common oxidation state shown by actinoids,
Q.29 What is the maximum oxidation state shown by actinoids?

Answer: The maximum oxidation state shown by actinoids is +7.
Q.30 What is the highest oxidation state shown by lanthanoids?

Answer: Highest oxidation state shown by lanthanoids = + 4.
Q.31 What is the minimum oxidation state shown by lanthanoids?

Answer: Minimum oxidation state shown by lanthanoids = +2.
Q.32 Name the components of steel.

Answer: 95% iron, 5% carbon Cr, Mn, Ni etc.
Q.33 Name the transition metal compound used in pigment industry.

Answer: TiO.
Q.34 Name the transition metals used in battery industries.

Answer: Ni and Cd.
Q.35 What are coinage metals? Why are they called so?

Answer: Elements of group -11 (Cu, Ag, Au) are called coinage metals. They are so called because they were used in making coins.
Q.36 Hyne to ethanol.

Answer: AgBr is used in photographic industry.
Q.37  In which industry AgBr is used?

Answer: Nickel.
Q.38 Transition metals have very high melting points and boiling points why?

Answer: The high melting point and boiling points of transition metals are attributed to the involvement of greater number of electrons from (n- 1) d-orbital in addition to the ns electrons in the inter atomic metallic bonding (d-d overlap).
Q.39 Transition metals have very high enthalpies of atomization, Why?

Answer: The high enthalpy of atomisation is due to stronger inter atomic bonding due to overlap of unpaired electrons in d-orbitals. Greater the number of unpaired electrons, stronger is the resulting bonding and corresponding higher enthalpy of atomisation.
Q.40 Enthalpies of atomisation of 2nd and 3rd transition series are higher than the corresponding metals of first transition series.

Answer: This fact can be explained on the basis that heavy transition metals have much more strong metal-metal bonding.
Q.41  Ionic radii of ions of the same charge decreases progressively with increasing atomic number in a series. Why?

Answer: As the atomic number increases the new electron enters the d-orbital. The nuclear charge increases. But due to poor shielding effect of d-orbital the electrostatic attraction between nucleus and outermost orbit increases and the ionic radius decreases.
Q.42 Density of transition metals increases from Ti to Cu.

Answer: As the atomic number increases from Ti to Cu, the metallic radius decrease and the atomic mass increases. So significant increase in density can be observed.
Q.43 How do ionisation enthalpy changes along a transition series?

Answer: Along left to right in each series of transition element there is an increase in ionisation enthalpy due to increase in nuclear charge.
Q.44 Transition metals show a great variety of oxidation states. Explain.

Answer: The transition metals show a great variety of oxidation states due to incomplete filling of d-orbitals.
Q.45 Transition metals show highest oxidation state in fluorides and oxides. Why?

Answer: The ability of fluorine to stabilize the highest oxidation state is due to higher lattice energy and higher bond enthalpy where as stability of oxide is due to its ability to form multiple bonding.
Q.46 What is the cause of paramagnetism?

Answer: Para magnetism arises from the presence of unpaired electrons, each unpaired electron has magnetic moment associated with its spin angular momentum and orbital angular momentum.
Q.47 Transition metal compounds are generally coloured, why?

Answer: Transition metal compounds are generally coloured, due to the presence of incomplete d-sub shell, i.e., there is d-d transition.
Q.48 Transition metals form a large number of complex compounds. Give reasons.

Answer: Transition metals form a large number of complex compounds due to following reasons:-

(i) Comparatively smaller size of metal ions. 

(ii) High ionic charges. 

(iii) Availability of d-orbitals for bond formation.
Q.49 Transition metals and their compounds act as catalyst. Why?

Answer: Transition metals and their compounds show catalytic property because they possess multiple oxidation states, form complexes and can adsorb the reactants at the surface.
Q.50 Transition metals form alloys readily. Why?

Answer: Due to similar atomic radii they are used in alloy formation.