Write structural formulas of the type indicated: (a) Bond-line formulas for seven constitutional isomers with the formula

Question:

Write structural formulas of the type indicated:
(a) Bond-line formulas for seven constitutional isomers with the formula C4H10O;
(b) Condensed structural formulas for two constitutional isomers with the formula C2H7N;
(c) Condensed structural formulas for four constitutional isomers with the formula C3H9N;
(d) Bond-line formulas for three constitutional isomers with the formula C5H12.