Question

The correct order of electropositive character of given elements is:

• A. $Li>Na>K>Rb>Cs$
• B. $Li<Na<K<Rb<Cs$
• C. $Li>Na<K<Rb<Cs$
• D. $Na>Li>K<Rb<Cs$

Answer 1

The correct option is B $Li<Na<K<Rb<Cs$

• Electropositive Character: Due to low ionisation energy, alkali elements lose the electrons very easily. Hence, they can be said as strongly electropositive. The electropositive character increases as we move down the group from $Li$ to $Cs$.
• Due to their strong electropositive nature, they emit electrons when exposed to light. This effect is termed as photo-electric effect. These elements are greatly used in photoelectric cells.
• As caesium and potassium are highly electropositive when compared to other elements, they are greatly used in the photoelectric cells when compared to other alkali metals.
  
• Hence the correct order is: $Li<Na<K<Rb<Cs$