What is the value of electron gain enthalpy of Na if IE1 of Na = 5.1 eV?
-5.1 eV
-10.2 eV
+2.55 eV
+10.2eV
Assertion (A): K, Rb and Cs form superoxides.
Reason (R): The stability of the superoxides increases from 'K' to 'Cs' due to decrease in lattice energy.
The correct answer is
Both (A) and (R) are true and (R) is the correct explanation of (A).
Both (A) and (R) are true but (R) is not the correct explanation of (A)
(A) is true but (R) is not true
(A) is not true but (R) is true
C.
(A) is true but (R) is not true
Superoxides are the species having an bond and O in an oxidation state of (superoxide ion is ). Usually these are formed by active metals such as KO2, RbO2 and CsO2. For the salts of larger anions (like ), lattice energy increases in a group. Since, lattice energy is the driving force for the formation of an ionic compound and its stability, the stability of the superoxides from 'K' to 'Cs' also increases.
Which one of the following order is correct for the first ionisation energies of the elements?
B <Be <N < O
Be <B <N < O
B <Be <O <N
B <O <Be <N
Ce4+ is stable. This is because of
half-filled d-orbitals
all paired electrons ind-orbitals
empty orbital
fully filled d-orbital