Which of the following is not a transition element ?

Which element does not show variable oxidation state ?

Which metal has highest density ?

KMnO₄, oxidation number of Mn is

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

Which of the following reactions are disproportionation reactions?
\((i)\ { Cu }^{ + }\longrightarrow { Cu }^{ 2+ }+{ Cu }\) 
\((ii)\ { 3MnO }_{ 4 }^{ - }+{ 4H }^{ + }\longrightarrow { 2MnO }_{ 4 }^{ - }+{ MnO }_{ 2 }+{ 2H }_{ 2 }O\) 
\((iii)\ { 2KMnO }_{ 4 }\longrightarrow { K }_{ 2 }{ MnO }_{ 4 }+{ MnO }_{ 2 }+{ O }_{ 2 }\) 
\((iv)\ { 2MnO }_{ 4 }^{ - }+{ 3Mn }^{ 2+ }+{ 2H }_{ 2 }O\longrightarrow { 5MnO }_{ 2 }+{ 4H }^{ + }\) 

Although +3 is the characteristic oxidation state for lanthanoids but cerium also shows +4 oxidation state because ......... .

When manganous salt is fused with a mixture of KNO₃ and solid NaOH, the oxidation number of Mn changes from +2 to

When pyrolusite id fused with KOH and KCIO₃, we get 

Mohr salt, FeSO₄, (NH₄)₂SO₄. 6 H₂ O, is preferred over FeSO₄. 7 H₂O for standardization of KMnO₄ solution because.

Most of the transition metal ions exhibit characterisitic  in colours in aqueous solutions. Give reason.

Why does copper not replace hydrogen from acids?

In the first transition series, the maximum number of oxidation states is shown by _______________.

Why Zr and Hf or Nb and Ta exhibit similar properties ?

Or Zirconium (atomic number 40) and hafnium (atomic number 72) occur together in minerals and they exhibit similar properties. Give reasons.

How would you account for the following?
(i) Cr²⁺ is reducing in nature while with the same d-orbital configuration (d⁴) Mn³⁺ is an oxidising agent.
(ii) In a transition series of metals, the metal which exhibits the greatest number of oxidation states occurs in the middle of the series.

Why is the +2 oxidation state of manganese quite stable, while the same is not true for iron? [Mn = 25, Fe = 26]

Write a note on lanthanoid contraction.

Why are Mn²⁺ compounds more stable than Fe²⁺ compounds towards oxidation to their +3 state ?

Give reasons:
(i) Mn shows the highest oxidation state of +7 with oxygen but with fluorine, it shows the highest oxidation state of +4.
(ii) Transition metals show variable oxidation states.
(iii) Actinoids show irregularities in their electronic configurations.

How would you account for the following?
(I) The E^o value for the Mn³⁺ /Mn²⁺ couple is much more positive than that for the Cr³⁺/Cr²⁺ couple or Fe ³⁺/Fe ²⁺ couple.
(ii) The highest oxidation state of a metal is exhibited in its oxide or fluoride.
(iii) The atomic radii ofthe metals ofthe third (Sd) series of transition elements are virtually the same as those of the corresponding members of the second (4d) series.

Identify the first row transition metal ions which have outer electronic configurations of 3d⁴ and 3d⁶ and describe their oxidation states. 

Why do the transition elements exhibit higher enthalpies of atomisation?

Although fluorine is more electronegative than oxygen, but the ability of oxygen to stabilise higher oxidation states exceeds that of fluorine. Why?

Zinc is a transition element and has many useful applications. The presence of zinc in trace amounts is essential in humans and many animals.
Answer the following questions:
(i) What is the role of zinc in the body of humans and animals?
(ii) A compound of zinc is used as a rodent poison. Name the compound.
(iii) Name the compound of zinc used in paints.
(iv) Is \(ZnSO_{ 4 }(aq)\) coloured or colourless? 

(a) Give reasons for the following:
(i) \(\\ Mn^{ 3+ }\) is a good oxidising agent.
(ii) \(E°_{ M^{ 2+ }/M }\) values are not regular for first row transition metals (3d series).
(iii) Although 'F' is more electronegative than 'O' the highest Mn fluoride is \(MnF_{ 4 }\),
(b) Complete the following equations:
(i) \(2CrO_{ 4 }^{ 2- }+2H^{ + }\longrightarrow \)
(ii) \(KMnO_{ 4 }\overset { Heat }{ \longrightarrow } \)

Lokesh is a social worker. A milkman in the village has been complaining that a factory in his nearby area dumps chemical waste in his field which has become a major cause of decreasing productivity. Lokesh visited that place and found after analysis that the major waste was potassium permanganate which is being absorbed by the soil. He advised the factory people that they should treat potassium permanganate solution before dumping it into the drain.
Comment in brief:
(i) About the environmental values displayed by Lokesh.
(ii) Write balanced chemical equations for the two reactions showing oxidizing nature of potassium permanganate.