Which alkali metal has the highest first ionisation enthalpy?

A $Cs$
B $Na$
C $Li$
D $K$

Answer: C

First ionisation enthalpy decreases down group 1 because the valence electron is farther from the nucleus and better shielded. Lithium, the smallest atom, therefore has the highest value, about

520 kJ mo l^{- 1}

Practice s-Block Elements More on General trends of alkali and alkaline earth metals

Previous questionNext question

More questions on General trends of alkali and alkaline earth metals

In a flame test, which ion imparts an apple-green colour to the flame? NEET level
Which of the following sets contains only properties that lithium shares with magnesium but not with sodium? JEE Advanced level
The solubility of the sulphates of group 2 decreases from Mg to Ba, whereas the solubility of the hydroxides increases. Which explanation is... JEE Advanced level
The enthalpy of sublimation, first ionisation enthalpy and hydration enthalpy of the gaseous ion (all in kJ mol^-1) are: Li (159, 520, -519)... JEE Advanced level
Which of the following statements about the alkaline earth metals and their compounds are correct? JEE Main level
Assertion (A): Lithium has the most negative standard electrode potential of all alkali metals (-3.04 V) even though it has the highest firs... JEE Main level