When MnO2 is fused with KOH, a colouredcompound is formed. The product and its colour is:
K2MnO4 , purple colour
Mn2O3 , brown
Mn2O4 , black
KaMnO4 , purple
H2C2O4 + KMnO4 in acidic medium reacts to have change in oxidation number of Mn from
7 to 5
2 to 7
5 to 7
7 to 2
Oxidation number of Cr in K2Cr2O7 is
2
4
6
7
C.
6
Oxidation number of Cr in K2Cr2O7 is
2(+1) + 22(x) + 7(-2) = 0
2 + 2x - 14 = 0
2x = 12
x = 6
Hence, 6 is the oxidation number of Cr.
For which of the following elements it is difficult to disproportionate in +3 oxidation state ?
N
As
Sb
Bi
Substances that are oxidised and reduced in the following reaction are respectively
N2H4 (l) + 2H2O2 (l) N2 (g) + 4H2O (l)
N2H4, H2O
N2H4, H2O2
N2, H2O2
H2O, N2