The electronic configuration of Cr3+ is
[Ar] 3d4 4s2
[Ar] 3d3 4s0
[Ar] 3d2 4s1
[Ar] 3d5 4s1
B.
[Ar] 3d3 4s0
Cr (24) = [Ar] 3d5 4s1
Cr3+ = [Ar] 3d3 4s0
The order of stability of metal oxides is
Al2O3 < MgO < Fe2O3 < Cr2O3
Cr2O3 < MgO < Al2O3 < Fe2O3
Fe2O3 < Cr2O3 < Al2O3 < MgO
Fe2O3 < Al2O3 < Cr2O3 < MgO
The oxide of an element whose electronic configuration is 1s2, 2s2, 2p6, 3s1 is
neutral
amphoteric
basic
acidic
The correct order of ionisation energy of C, N, O, F is
F < O < N < C
F < N < C < O
C < N < O < F
C < O < N < F
Generally, the first ionisation energy increases along a period. But there are some exceptions. The one which is not an exception is
Be and B
Na and Mg
Mg and Al
N and O
The correct order of electronegativities of N, O, F and P is
F > O > P > N
F > O > N > P
N > O > F > P
F > N > P > O
An ionic compound is expected to have tetrahedral structure if r+/r- lies in the range of
0.414 to 0.732
0.225 to 0.414
0.155 to 0.225
0.732 to 1
Carbon can reduce ferric oxide to iron at a temperature above 983 K because
carbon monoxide formed is thermodynamically less stable than ferric oxide
carbon has a higher affinity towards oxidation than iron
free energy change for the formation of carbon dioxide is less negative than that for ferric oxide
iron has a higher affinity towards oxygen than carbon