1

NEET 2021

MCQ (Single Correct Answer)
From the following pairs of ions which one is not an iso-electronic pair?
A
Fe2+, Mn2+
B
O2$$-$$, F$$-$$
C
Na+, Mg2+
D
Mn2+, Fe3+

Explanation

$$\bullet$$ Isoelectronic species have some number of electrons.

2

NEET 2020 Phase 1

MCQ (Single Correct Answer)
Match the following :
Oxide Nature
(A) CO (i) Basic
(B) BaO (ii) Neutral
(C) Al2O3 (iii) Acidic
(D) Cl2O7 (iv) Amphoteric

Which of the following is correct option?
A
(A) (B) (C) (D)
(ii) (i) (iv) (iii)
B
(A) (B) (C) (D)
(iii) (iv) (i) (ii)
C
(A) (B) (C) (D)
(iv) (iii) (ii) (i)
D
(A) (B) (C) (D)
(i) (ii) (iii) (iv)

Explanation

CO : Neutral oxide
BaO : Basic oxide
Al2O3 : Amphoteric oxide
Cl2O7 : Acidic oxide
3

NEET 2020 Phase 1

MCQ (Single Correct Answer)
Identify the incorrect match.
Name IUPAC Official Name
(A) Unnilunium (i) Mendelevium
(B) Unniltrium (ii) Lawrencium
(C) Unnilhexium (iii) Seaborgium
(D) Unununnium (iv) Darmstadtium
A
(B), (ii)
B
(C), (iii)
C
(D), (iv)
D
(A), (i)

Explanation

Unununnium
Atomic number = 111
IUPAC official name : Roentgenium (Rg) not Darmstadtium.
4

NEET 2019

MCQ (Single Correct Answer)
For the second period elements the correct increasing order of first ionization enthalpy is :
A
Li < B < Be < C < N < O < F < Ne
B
Li < Be < B < C < O < N < F < Ne
C
Li < B < Be < C < O < N < F < Ne
D
Li < Be < B < C < N < O < F < Ne

Explanation

Ionisation enthalpy increases in a period from left to right, because of increased nuclear charge and decrease in atomic radii. But because of half filled orbitals of Be, N and fully filled orbitals of Ne, stability of those atoms inceases.

So, the correct increasing order of first ionisation enthalpy will be :
Li < B < Be < C < O < N < F < Ne

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