NEET UG CHEMISTRY MCQ: STRUCTURE OF ATOM

1 Hard

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Understanding +4 | -1

Which of the following statements are correct?

(i) The second period

(n=2)

starts with lithium and third electron enters the

2 s

orbital. The next element, beryllium has four electrons and has the electronic configuration

1 s^2 2 s^2

. From the next element boron, the

2 p

orbitals are filled with electrons when the

\mathrm{L}

shell is completed at neon

\left(2 s^2 2 p^6\right)

. Thus there are 8 elements in the second period.

(ii) Successive filling of

3 s

and

3 p

orbitals gives rise to the third period of 8 elements from sodium to argon.

(iii) The fourth period

(n=4)

starts at potassium and the added electron fill up the first

4 s

and

4 p

orbitals than

3 d

orbital is filled.

(iv) Fifth period begins with rubidium with the filling of

5 \mathrm{~s}

orbital and ends at xenon with the filling up of the

5 p

orbital.

View answer and explanation

Correct option: D

(i), (ii) and (iv)

Option D ((i), (ii) and (iv)) is correct because statements (i), (ii), and (iv) accurately describe the filling of electron orbitals in the second, third, and fifth periods, respectively. Statement (iii) is incorrect.

NEET UG CHEMISTRY MCQ: STRUCTURE OF ATOM

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