Which one of the following elements will require the highest energy to take out an electron from them ? Pb, Ge, C and Si

Question

MCQ (Single)Classification of Materials as Conductors, Semiconductors and InsulatorsCBSE PYQ

C and Si both have the same lattice structure, but C is an insulator while Si is a semiconductor. Justify.

What happens to the fringe pattern if one of the slits in Young's double slit experimental set-up is closed ?