Classification of Elements and Periodicity in Properties NEET PYQs (1989–2026)

Solved Classification of Elements and Periodicity in Properties PYQs

3 recent questions with answers. The full set of 57 is free to practise.

1. NEET 2026HardIonization Enthalpy
   Q1

   Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R.
   
   Assertion A: The first ionization enthalpy of O is lower than that of N and F.
   
   Reason R: The loss of an electron from O leads to stable half-filled p orbital.
   
   In light of the above statements, choose the most appropriate answer from the options given below:

   • ABoth A and R are correct and R is the correct explanation of A
   • BBoth A and R are correct and R is NOT the correct explanation of A
   • CA is correct but R is not correct
   • DA is not correct but R is correct

   Show answer & solution

   Correct answer: (A)

   O: 1s²2s²2p⁴. Removing one electron gives 2p³ (half-filled). So ionization enthalpy of O is lower than N (2p³) and F (2p⁵). Reason is correct explanation.
2. NEET 2026EasyPeriodic Trends
   Q2

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

   • AF > Cl > Br > I
   • BBr > Cl > F > I
   • CCl > F > Br > I
   • DI > Br > Cl > F

   Show answer & solution

   Correct answer: (C)

   Electron gain enthalpy: Cl > F > Br > I (F is less than Cl due to small size and electron-electron repulsion). So option (3).
3. NEET 2026MediumAtomic and Ionic Radii
   Q3

   Identify the incorrect statement from the following:

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

   Show answer & solution

   Correct answer: (A)

   Largest species is Mg (since it has largest size among these), smallest is Al³⁺. So statement (1) is incorrect.

Topic-wise question count

Where NEET has asked from Classification of Elements and Periodicity in Properties, most frequent first.

• Periodic Trends19
• Atomic and Ionic Radii12
• Periodic Classification10
• Ionization Enthalpy5
• Nature of Oxides4
• Electronegativity3
• Periodic Properties2
• Electronic Configuration1
• Isoelectronic Species1

Year-wise Classification of Elements and Periodicity in Properties questions in NEET

Number of questions from this chapter in each year's paper(s).