JEE Main · 2021 · 18 Mar 2021 · Shift 2 · Classification of Elements and Periodicity

The first ionization energy of magnesium is smaller as compared to that of elements

X

and

Y

, but higher than that of

Z

. The elements

X, Y

and

Z

, respectively are:

(A)argon, chlorine and sodium✓ Correct
(B)chlorine, lithium and sodium
(C)neon, sodium and chlorine
(D)argon, lithium and sodium

Answer: (A)

Solution

Ionisation energy rises from left to right across a period and falls down a group. Sodium is the element immediately preceding magnesium in the third period and gives up its single

3 s

electron more easily, so its ionisation energy lies below that of magnesium. Chlorine lies further to the right in the same period and argon closes it with a filled

3 s^{2} 3 p^{6}

shell, so both demand more energy than magnesium, argon most of all. The elements are argon, chlorine and sodium.

JEE Main · 2021 · 18 Mar 2021 · Shift 2 · Single correct option

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JEE Main · 2021 · 18 Mar 2021 · Shift 2 · Classification of Elements and Periodicity

Solution

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