Multiple Choice QuestionsAn f-shell containing 6 unpaired electrons can exchange
6 electrons
9 electrons
12 electrons
15 electrons
Among the elements Ca, Mg, P and Cl, the order of increasing atomic radii is
Mg< Ca< Cl< P
Cl <P <Mg< Ca
P <Cl< Ca< Mg
Ca <Mg <P < Cl
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
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
C.
B <Be <O <N
D.
B <O <Be <N
First ionisation energy increases in a period. Thus, the first IE of the elements of the second period should be as follows
Be <B <N <O
But in practice, the elements do not follow the above order. The first IE of these elements is
B <Be <O < N
The lower IE of B than that of Be is because in B (1s2, 2s2,2p1), electron is to be removed from 2p which is easy while in Be (1s2, 2s2), electron is to be removed from 2s which is difficult. The low IE of O than that of N is because of the half-filled 2p orbitals in N (1s2, 2s2,2p3).
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