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
B.
Cl <P <Mg< Ca
With increase in the number of electrons in the same shell, the atomic radii decreases due to increase in effective nuclear charge. However, atomic radii increases, as the number of shells increases. Thus, on moving down a group atomic radii increases. The electronic configuration of the given element is
Mg12 = [Ne] 3s2
Ca20 = [Ar]4s2
P15 = [Ne] 3s2 3p2
Cl17 = [Ne]3s2 3p5
In Mg, P and Cl, the number of electrons are increasing in the same shell, thus the order of their atomic radii is
Cl <P < Mg
In Ca, the electron is entering in higher shell, thus, it has the highest atomic radii among the given. Thus, the order of radii is
Cl<P <Mg< Ca
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
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