(A) The ionisation potential (or ionisation energy) decreases down a group and increases across a period from left to right. Group $I$ elements (alkal

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(A) The ionisation potential (or ionisation energy) decreases down a group and increases across a period from left to right. Group $I$ elements (alkali metals) have the largest atomic size in their respective periods and the lowest effective nuclear charge,which results in the lowest ionisation potential values. Therefore,the correct option is $(a)$.

Class 11 Chemistry Classification of Elements and Periodicity in Properties Ionisation energy

Easy

In the long form of the periodic table,the elements having the lowest ionisation potentials are present in:

A
$I$ group
B
$IV$ group
C
$VII$ group
D
Zero group

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Class 11 Questions

Class 11

Chemistry Questions

Chapter

Classification of Elements and Periodicity in Properties

Subtopic

Ionisation energy

The $1^{st}$ ionization enthalpy for $Mg$ is $+737 \text{ kJ/mol}$. The most probable estimated value of the $2^{nd}$ ionization enthalpy of $Mg$ is . . . . . . .

MediumJEE MAIN 2026

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For one of the elements,various successive ionization enthalpies (in $kJ \cdot mol^{-1}$) are given below:

$I.E.$ $1^{st}$ $2^{nd}$ $3^{rd}$ $4^{th}$ $5^{th}$

Value $577.5$ $1810$ $2750$ $11580$ $14820$

The element is:

MediumKCET 2015

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The atomic numbers of elements $X, Y$,and $Z$ are $19, 37$,and $55$ respectively. Which of the following statements is correct?

Difficult

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Which of the following elements are at the peaks of the ionization energy trend?

Medium

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Which of the following electronic configurations represents the atom with the lowest first ionization enthalpy?

Medium

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$I.E.$	$1^{st}$	$2^{nd}$	$3^{rd}$	$4^{th}$	$5^{th}$
Value	$577.5$	$1810$	$2750$	$11580$	$14820$

In the long form of the periodic table,the elements having the lowest ionisation potentials are present in:

Similar Questions

The $1^{st}$ ionization enthalpy for $Mg$ is $+737 \text{ kJ/mol}$. The most probable estimated value of the $2^{nd}$ ionization enthalpy of $Mg$ is . . . . . . .

For one of the elements,various successive ionization enthalpies (in $kJ \cdot mol^{-1}$) are given below: $I.E.$ $1^{st}$ $2^{nd}$ $3^{rd}$ $4^{th}$ $5^{th}$ Value $577.5$ $1810$ $2750$ $11580$ $14820$ The element is:

The atomic numbers of elements $X, Y$,and $Z$ are $19, 37$,and $55$ respectively. Which of the following statements is correct?

Which of the following elements are at the peaks of the ionization energy trend?

Which of the following electronic configurations represents the atom with the lowest first ionization enthalpy?

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For one of the elements,various successive ionization enthalpies (in $kJ \cdot mol^{-1}$) are given below:

$I.E.$ $1^{st}$ $2^{nd}$ $3^{rd}$ $4^{th}$ $5^{th}$

Value $577.5$ $1810$ $2750$ $11580$ $14820$

The element is: