1) The radius of the 2nd orbit of B4+ ion is A) 4.23 Å B) 0.2340Å C) 0.4232Å D) 0.3241Å Answer: Option CExplanation:Radius of the nth orbit (rn)= 0.529×n2Z Å For B4+ion, (Z) =5, second orbit (n)=2 r2(B4+)=0.529×(2)25 Å= 0.529×45Å r2(B4+)= 0.4232 Å