When H2O2 is shaken with an acidified solution of K2Cr2O7 in the presence of ether, the ethereal layer turns blue due to the formation of
Cr2O3
Cr2(SO4)3
CrO5
Anhydrous ferric chloride is prepared by
dissoving Fe(OH)3 in concentrated HCl
dissolving Fe(OH)3 in dilute HCl
passing dry HCl over heated iron scrap
passing dry Cl2 gas over heated iron scrap
Transition elements exhibit variable valencies, because they release electrons from the following orbits
ns
ns and np
(n - 1) d and ns
nd and (n - 1)d
Although zirconium belongs to 4d and hafnium belongs to 5d transition series even they show similar physical and chemical properties because both
belong to d- block
have same number of electrons
belongs to the same group of the periodic table
have similar atomic radius
Which of the following will not give tests for free transition metal ion in solution ?
K2[Ni(CN)4]
FeSO4.K2SO4.24H2O
Both of the above
None of the above
Zinc oxide loses oxygen on heating according to the reaction
It becomes yellow on heating because
Zn2+ ions and electrons move too interstitial sites and F-centres are created.
Oxygen and electron moves at the crystal and ions become yellow
Zn2+ again combine with oxygen to give yellow oxide
Zn2+ are replaced by oxygen.
A.
Zn2+ ions and electrons move too interstitial sites and F-centres are created.
Zn2+ ions and electrons move to interstitial sites and F-centres are created which impart yellow colour to ZnO.