Advertisements
Advertisements
प्रश्न
Which of the d-block elements may not be regarded as the transition elements?
Advertisements
उत्तर
The electronic configuration of Zn, Cd and Hg is represented by the general formula (n – 1)d10ns2. In these elements, the orbitals are completely filled in the ground (normal) state as well as in ordinary oxidation states, i.e., the subshells are not incomplete in their atomic state or any one of the ionic states. Therefore, they cannot be called transition elements.
संबंधित प्रश्न
Complete the following chemical equations:
`(i) Cr_2O_7^(2-)+6Fe^(2+)+14H^+ ->`
`(ii) 2CrO_4^(2-)+2H^+ ->`
`(iii) 2MnO_4^-+5C_2O_4^(2-)+16H^+ ->`
Calculate magnetic moment of `Fe_((aq))^(2+) ion (Z=26).`
Account for the following:
Cr2+ is a strong reducing agent.
The elements of 3d transition series are given as: Sc Ti V Cr Mn Fe Co
Answer the following: Which element has the highest m.p?
How would you account for the irregular variation of ionization enthalpies (first and second) in the first series of the transition elements?
How is the variability in oxidation states of transition metals different from that of the non-transition metals? Illustrate with examples.
Predict which of the following will be coloured in the aqueous solution?
Ti3+, V3+, Cu+, Sc3+, Mn2+, Fe3+ and Co2+. Give reasons for each.
How would you account for the following?
Zr (Z = 40) and Hf (Z = 72) have almost identical radii.
An analysis shows that FeO has a non-stoichiometric composition with formula Fe0.95O. Give reason.
How is potassium dichromate prepared from chrome iron ore?
In lake test for Al3+ ions, there is the formation of coloured ‘floating lake’. It is due to ______.
Transition elements form binary compounds with halogens. Which of the following elements will form \[\ce{MF3}\] type compounds?
(i) \[\ce{Cr}\]
(ii) \[\ce{Co}\]
(iii) \[\ce{Cu}\]
(iv) \[\ce{Ni}\]
A violet compound of manganese (A) decomposes on heating to liberate oxygen and compounds (B) and (C) of manganese are formed. Compound (C) reacts with KOH in the presence of potassium nitrate to give compound (B). On heating compound (C) with conc. \[\ce{H2SO4}\] and \[\ce{NaCl}\], chlorine gas is liberated and a compound (D) of manganese along with other products is formed. Identify compounds A to D and also explain the reactions involved.
Account for the following:
In case of transition elements, ions of the same charge in a given series show progressive decrease in radius with increasing atomic number.
A metallic ion 'M' reacts with chloride ion to form white precipitate which is readily soluble in aqueous ammonia. Identify 'M'?
If enthalpies of formation of C2H4(g), CO2(g) and H2O(l) at 25°C and 1 atm pressure are 52, – 394 and – 286 kJ/mol respectively, the change in ethalpy for combustion of C2H4 is equal to
Account for the following:
Ce4+ is a strong oxidising agent.
Complete the following reaction and justify that it is a disproportionation reaction:
\[\ce{3MnO^{2-}4 + 4H^+ -> \underline{}\underline{}\underline{}\underline{} + \underline{}\underline{}\underline{}\underline{} + 2H2O}\]
Consider the following standard electrode potential values:
\[\ce{Sn^{2+}_{ (aq)} + 2e^- -> Sn_{(s)}}\]; E0 = −0.14 V
\[\ce{Fe^{3+}_{ (aq)} + e^- -> Fe^{2+}_{ (aq)}}\]; E0 = +0.77 V
What is the cell reaction and potential for the spontaneous reaction that occurs?
