C, Si and Ge have same lattice structure. Why is C insulator while Si and Ge intrinsic semiconductors?

Explain i. Oxides of nitrogen have open chain structures while those of phosphorus have closed chain or cage structure. Why is it so? IIustrate with one structural example for each type of oxides or The oxides of phosphorus have cage strućtures but not open ones. ii. Elemental phosphorus does not exist as P_2 as N_2

In the picture below, the lines, parallel to side of triangle A B C through the оррosite vertex are drawn to make the triangle PQR. a) Draw this picture, Draw the lines BQ, CP and AR. b) The triangles. ABP, AQC and BRC have the same arẹa as that of triangle A B C. Why? c) Find another 4 triangles of same area as that of triangle A B C from the picture which you have drawn and write their names.

A solid has a structure in which W atoms are located at the C0rners of a lattice, O atoms at the centre of the edges and Na atom at the centre of the cube. The formula of the compound is