Assertion (A): The highest oxidation state of osmium is +8.
Reason (R): Osmium is a 5d-block element.
(b) The highest oxidation state of osmium is +8 due to its ability to expand their octet by using its all 8 electrons.
Assertion (A): Cu can not libirate hydrogen from acids .
Reason (R): because it has positive electrode potential.
While filling up of electrons in the atomic orbitals, the 4s orbital is filled before the 3d-orbital but reverse happens during the ionization of the atom. Explain why?
Silver atom has completely filled d orbitals (4d10) in its ground state. How can you say that it is a transition element?
The halides of transition elements become more covalent with increasing oxidation state of the metal. Why?
When a brown compound of manganese
(A) is treated with HCl, it gives a gas
(B) The gas taken in excess, reacts with NH3 to give an explosive compound
(C) Identify compounds A, B and C.
Explain why does colour of KMnO4 disappear when oxalic acid is added to its solution in acidic medium?
A solution of KMnO4 on reduction yields either a colourless solution or a brown precipitate or a green solution depending on pH of the solution. What different stages of the reduction do these represent and how are they carried out?
When an oxide of manganese (A) is fused with KOH in the presence of an oxidizing agent and dissolved in water, it gives a dark green solution of compound (B). Compound (B) disproportionates in neutral or acidic solution to give purple compound (C). An alkaline solution of compound (C) oxidises potassium iodide solution to a compound (D) and compound (A) is also formed. Identify compounds A to D and also explain the reactions involved.
Calculate the number of unpaired electrons in the following gaseous ions : Mn3+, Cr3+, V3+ and Ti3+. Which one of these is the most stable in aqueous solution.
Compare the stability of +2 oxidation state for the elements of the first transition series.
The chemistry of the actinoid elements is not so smooth as that of the lanthanoids. Justify this statement by giving some examples from the oxidation state of these elements.
Compare the chemistry of actinoids with that of lanthanoids with reference to:
(i) Electronic configuration
(ii) Oxidation states
(iii) Chemical reactivity
In the form of dichromate, Cr (VI) is a strong oxidizing agent in acidic medium but Mo (VI) in MoO3 and W (VI) in WO3 are not because
(a) Cr (VI) is more stable than Mo(VI) and W(VI)
(b) Mo(VI) and W(VI) are more stable than Cr(VI)
(c) higher oxidation states of heavier members of group-6 of transition series are more stable
(d) lower oxidation states of heavier members of group-6 of transition series are more stable
Which of the 3d series of the transition metals exhibits the largest number of oxidation states and why?
Although +3 is the characteristic oxidation state for lanthanoids but cerium
also shows +4 oxidation state because
(a) it has variable ionization enthalpy
(b) it has a tendency to attain noble gas configuration
(c) it has a tendency to attain f ° configuration
(d) it resembles Pb4+
Although +3 oxidation states is the characteristic oxidation state of lanthanoids but cerium shows +4 oxidation state also. Why?
(a) Answer the following questions:
(i) Which element of the first transition series has highest second ionization enthalpy?
(ii) Which element of the first transition series has highest third ionization enthalpy?
(iii) Which element of the first transition series has lowest enthalpy of atomization?
(b) Identify the metal and justify your answer:
(i) Carbonyl M(CO)5 (ii) MO3F
(a) Transition metals can act as catalysts because these can change their oxidation state.
How does Fe(III) catalyse the reaction between iodide and persulphate ions?
(b) Mention any three processes where transition metals act as catalysts.
To what extent do the electronic configurations decide the stability of oxidation states in the first series of the transition elements? Illustrate your answer with examples.
How is the variability in oxidation states of transition metals different from that of the non transition metals? Illustrate with examples.
Indicate the steps in the preparation of:
(i) K2Cr207from chromite ore
(ii) KMn04 from pyrolusite ore.
What are alloys? Name an important alloy which contains some of the lanthanoid metals. Mention its uses.
Which is the last element in the series of the actinoids? Write the electronic configuration of this element. Comment on the possible oxidation state of this element
Generally, transition-elements and their salts are coloured due to the presence of unpaired electrons in metal ions. Which of the following compounds are coloured?
(a) kMnO4 (b) Ce(SO4)2 (c) TiCl4 (d) Cu2Cl2
Which of the following actinoids show oxidation states up to +7?
(a) Am (b) Pu (c) U (d) Np
Which of the following will not act as oxidizing agents?
(a) CrO3 (b) MoO3(c) WO3 (d) CrO42-
Name the oxometal anions of the first series of the transition metals in which the metal exhibits the oxidation state equal to its group number.
Predict which of the following will be coloured in aqueous solution? Ti3+, V3+,Cu+, Sc3+, Mn2+, Fe3+ and Co2+ Give reasons for each.
Compare the chemistry of actinoids with that of the lanthanoids with special reference to
(i) electronic configuration,
(ii) atomic and ionic sizes and
(iii) oxidation state
(iv) chemical reactivity.
Calculate the number of unpaired electrons in the following gaseous ions : Mn3+, Cr3+, V3+ and Ti3+. Which one of these is the most stable in aqueous solution.
The second and third rows of tfansition elements resemble each other much more than they resemble the first row. Explain why?
Explain giving reasons:
(i)Transition metals and many of their compounds show paramagnetic behaviour.
(ii)The enthalpies of atomisation of the transition metals are high.
(iii)The transition metals generally form coloured compounds.
(iv)Transition metals and their many compounds act as good catalyst
Predict which of the following will be coloured in aqueous solution? Ti3+, V3+,Cu+, Sc3+, Mn2+, Fe3+ and Co2+ Give reasons for each.
Name the members of the lanthanoid series which exhibit+4oxidatk>nstatesandthosewhichexhibit +2 oxidation states. Try to correlate this type of behaviour with the electronic configurations of these elements.
Although Zr belongs to 4d and Hf belongs to 5d transition series but it is quite difficult to separate them. Why?
On the basis of lanthanoid contraction, explain the following:
(a) Nature of bonding in La2O3 and Lu2O3.
(b) Trends in the stability of oxo-salts of lanthanoids from La to Lu.
(c) Stability of the complexes of lanthanoids.
(d) Radii of Ad- and 5d-block elements.
(e) Trends in acidic character of lanthanoid oxides.
What may be the stable oxidation state of the transition element with the following delectron configurations in the ground state of their atoms: 3d3,3d5, 3d8 and 3d4?
What is meant by disproportionation? Give two examples of disproportionation reaction in aqueous solution.
Use Hund's rule to derive the electronic configuration of Ce3+ ion, and calculate its magnetic moment on the basis of ‘spin-only' formula.
Transition elements show magnetic moment due to spin and orbital motion of electrons. Which of the following metallic ions have almost same spin only magnetic moment?
(a) Co2+ (b) Cr2+ (c) Mn2+ (d) Cr3+
General electronic configuration of actinoids is (n – 2)f1-14 (n – 1 )d0-2 ns2. Which of the following actinoids have one electron in 6d orbital?
(a) U (Atomic no. 92) (b) Np (Atomic no. 93)
(c) Pu (Atomic no. 94) (d) Am (Atomic no. 95)
