Advertisements
Advertisements
प्रश्न
Which of the following will not act as oxidising agents?
(i) \[\ce{CrO3}\]
(ii) \[\ce{MoO3}\]
(iii) \[\ce{WO3}\]
(iv) \[\ce{CrO^{2-}4}\]
Advertisements
उत्तर
(ii)\[\ce{MoO3}\]
(iii) \[\ce{WO3}\]
Explanation:
A compound act as oxidising agent when it’s central atom is reduced to its lower oxidation state. This occurs only when the lower oxidation state of metal is more stable than the higher oxidation states.
In metal \[\ce{WO3}\] and \[\ce{CrO4^{2-}}\], both W and Cr are stable in their higher oxidation state and won’t get reduced to their lower oxidation state. Therefore, will not act as oxidising agents.
APPEARS IN
संबंधित प्रश्न
Why do interstitial compounds have higher melting points than corresponding pure metals?
Which of the following cations are coloured in aqueous solutions and why ?
Sc3+, V3+, Ti4+, Mn2+ (At. Nos. Sc = 21, V = 23, Ti = 22, Mn = 25)
Why do the transition elements have higher enthalpies of atomisation?
In 3d series (Sc to Zn), which element has the lowest enthalpy of atomisation and why?
Explain briefly how +2 state becomes more and more stable in the first half of the first row transition elements with increasing atomic number?
Compare the stability of +2 oxidation state for the elements of the first transition series.
How would you account for the following:
The d1 configuration is very unstable in ions.
Complete and balance the following chemical equations
`Fe^(2+) + MnO_4^(-) + H^+ ->`
Two metallic elements A and B have the following standard oxidation potentials: A = 0·40v B = - 0·80v. What would you expect if element A was added to an aqueous salt solution of element B? Give a reason for your answer.
Out of \[\ce{Cu2Cl2}\] and \[\ce{CuCl2}\], which is more stable and why?
Ionisation enthalpies of Ce, Pr and Nd are higher than Th, Pa and U. Why?
The halides of transition elements become more covalent with increasing oxidation state of the metal. Why?
Answer the following question:
Which element of the first transition series has highest second ionisation enthalpy?
Transition metals can act as catalysts because these can change their oxidation state. How does \[\ce{Fe(III)}\] catalyse the reaction between iodide and persulphate ions?
Complete the following reaction and justify that it is a disproportionation reaction:
\[\ce{3MnO^{2-}4 + 4H^+ -> \underline{}\underline{}\underline{}\underline{} + \underline{}\underline{}\underline{}\underline{} + 2H2O}\]
The given graph shows the trends in melting points of transition metals:

Explain the reason why Cr has the highest melting point and manganese (Mn) has a lower melting point.
Which of the following ions has the electronic configuration 3d6?
(Atomic number: Mn = 25, Co = 27, Ni = 28)
The trend of which property is represented by the following graph?

What is the oxidation state of chromium in chromate ion and dichromate ion?
Compare the general characteristics of the first series of the transition metals with those of the second and third series metals in the respective vertical columns. Give special emphasis on the following point:
Atomic sizes
