Among the elements `B, AI,C` and `Si`,
(i) Which elements has the highest first ionisation enthaloy?
(ii) When element has the most metallic character? Justify your answer in each case.

Explanation

Arranging the elements B, A1 , C and Si into different groups and periods in order of their increasing atomic number we have ,
`{:(" Group " to ,,13,,14),("Period " 2 ,,B,,C),("Group " 3 ,,A1,,Si):}`
(i) Since ionization enthalpy increases along a period and decreases down a group therefore C has the highest first ionization enthalpy
(ii) Since metallic character increases down a group and decreases along a period therefore A1 is the most metallic element .