NEET2002ChemistryClassification of Elements and Periodicity in PropertiesActual
Which of the following order is wrong?
Options
- ANH ₃ < PH ₃ < AsH ₃ - Acidic
- BLi < Be < B < C - First ionization potential
- CAl ₂ O ₃ < MgO < Na ₂ O < K ₂ O - Basic
- DLi ⁺ < Na ⁺ < K ⁺ < Cs ⁺- Ionic radius
Correct answer
B. Li < Be < B < C - First ionization potential
Step-by-step solution
Li , Be , B , C - these elements belong to the same period. Generally, the value of 1 st ionisation potential increases in moving from left to right in a period, since the nuclear charge of the elements also increase in the same direction. But the ionisation potential of boron ( B 2 s^2 p^1 ) is lower than that of beryllium (Be 2 s^2 ), since in case of boron, 2 p^1 electron have to be removed to get B ⁺ , while in case of Be , 2 s^2 electron have to be removed to get Be ⁺ (2 s^1 ) . p electron can be removed more