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JEE Mains · Chemistry · STD 11 - 3. Classification of elements and periodicity in properties

Given below are two statements :
Statement (I) : The first ionisation enthalpy of the elements Na, Mg, Cl and Ar follows the order Na \(>\) Mg \(>\) Cl \(>\) Ar.
Statement (II) : Among Ca, Al, Fe and B, the third ionisation enthalpy is very high for Ca.
In the light of the above statements, choose the correct answer from the options given below :

  1. A Both Statement I and Statement II are true
  2. B Both Statement I and Statement II are false
  3. C Statement I is true but Statement II is false
  4. D Statement I is false but Statement II is true
Verified Solution

Answer & Solution

Correct Answer

(D) Statement I is false but Statement II is true

Step-by-step Solution

Detailed explanation

The first ionisation enthalpy generally increases across a period from left to right due to an increase in effective nuclear charge. For the third period elements \(\text{Na}\), \(\text{Mg}\), \(\text{Cl}\), and \(\text{Ar}\), the correct order of first ionisation enthalpy is…