The heat combustion of acetylene, c2h2(g), at 25°c, is –1299 kj/mol. at this temperature, δhvalues for co2(g) and h2o(l) are –393 and –286 kj/mol, respectively. calculate δhfor acetylene.

18

step-by-step explanation:

draw the shape and you will see that f and k are actually at adjacent vertices (points of the hexagon that are neighboring).   so find the distance between (1,2) and (4,2).   that is easy since (1,2) and (4,2) is just a vertical distance to count, which is 3.   it is a regular polygon which means all sides are congruent.   you have 6 sides (hexa) so multiply 6 by 3 to receive 18.