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Classification of Elements and Periodicity in Properties · Question 2

NEET (UG) 2026MCQMedium📈 Topic in 38% papers+4−1
1

Identify the incorrect statement from the following:

  1. The largest and the smallest species among Mg, Mg2+, Al and Al3+ are Al and Mg2+, respectively.
  2. The IUPAC name of the element with atomic number 107 is Unnilseptium.
  3. The similarity in behaviour of Li with Mg is referred to as 'diagonal relationship'.
  4. The oxidation state and covalency of Al in [AlCl(H2O)5]2+ are 3 and 6 respectively.

Answer

(1) The largest and the smallest species among Mg, Mg2+, Al and Al3+ are Al and Mg2+, respectively.

Solution

(1) Cations are smaller than their atoms, and across a period size falls: Mg > Al.

Mg2+ and Al3+ are isoelectronic (10 electrons); higher nuclear charge ⇒ smaller ion ⇒ Al3+ < Mg2+.

∴ Size order: Mg > Al > Mg2+ > Al3+ ⇒ largest = Mg, smallest = Al3+. Statement (1) is incorrect.

(2) 1 = un, 0 = nil, 7 = sept ⇒ Unnilseptium (symbol Uns): correct.

(3) As per NCERT, the similarity of Li with Mg (and Be with Al) is called the diagonal relationship: correct.

(4) In [AlCl(H2O)5]2+: x − 1 + 0 = +2 ⇒ x = +3; six ligands are bonded ⇒ covalency 6: correct.

Answer: (1)

NEET (UG) 2026

Keep practising — Classification of Elements and Periodicity in Properties

2

Among the following options, the correct trend in the electron gain enthalpy is

  1. I > Br > Cl > F
  2. F > Cl > Br > I
  3. Br > Cl > F > I
  4. Cl > F > Br > I
RE-NEET (UG) 2026
3

Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R. In light of the above statements, choose the most appropriate answer from the options given below:

  1. A is not correct but R is correct
  2. Both A and R are correct and R is the correct explanation of A
  3. Both A and R are correct and R is NOT the correct explanation of A
  4. A is correct but R is not correct.
RE-NEET (UG) 2026
4

Which of the following statements are true? Choose the correct answer from the options given below :

  1. C and D only
  2. A, C, and E only
  3. A, B, and E only
  4. C and E only
NEET (UG) 2025
5

Which among the following electronic configurations belong to main group elements? Choose the correct answer from the option given below :

  1. D and E only
  2. A, C and D only
  3. B and E only
  4. A and C only
NEET (UG) 2025
6

Arrange the following elements in increasing order of first ionization enthalpy: Li, Be, B, C, N Choose the correct answer from the options given below:

  1. Li < Be < B < C < N
  2. Li < B < Be < C < N
  3. Li < Be < C < B < N
  4. Li < Be < N < B < C
NEET (UG) 2024
7

Arrange the following elements in increasing order of electronegativity: N, O, F, C, Si Choose the correct answer from the options given below :

  1. Si < C < N < O < F
  2. Si < C < O < N < F
  3. O < F < N < C < Si
  4. F < O < N < C < Si
NEET (UG) 2024
8

The correct decreasing order of atomic radii (pm) of Li, Be, B and C is

  1. Be > Li > B > C
  2. Li > Be > B > C
  3. C > B > Be > Li
  4. Li > C > Be > B
RE-NEET (UG) 2024
9

Match List I with List II: Choose the correct answer from the options given below:

  1. A-I, B-II, C-IV, D-III
  2. A-I, B-IV, C-III, D-II
  3. A-I, B-IV, C-II, D-III
  4. A-IV, B-I, C-II, D-III
RE-NEET (UG) 2024
10

The element expected to form largest ion to achieve the nearest noble gas configuration is

  1. F
  2. N
  3. Na
  4. O
NEET (UG) 2023
11

The IUPAC name of an element with atomic number 119 is

  1. ununennium
  2. unnilennium
  3. unununnium
  4. ununoctium
NEET (UG) 2022

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