double bonds, but no single bonds. The answer is (A).- B Determine the structure of SO 2 . Sulfur is the central atom, and each
atom has 6 valence electrons. Arranging them all so that they have octets
gives you
Notice that there are three electron pair sites around the
central sulfur atom (a double or triple bond counts as
only one site), one of which is a lone pair. This will
result in a bent shape, so (B) is correct.- E In the course of this reaction, 4 moles of C–H bonds and 1 mole of
Cl–Cl bonds are broken. So 4(410 kJ) + 240 kJ, or 1,880 kJ, are needed to
break these bonds. The reaction produces 1 mole of C–Cl bonds, 1 mole of
H–Cl bonds, and 3 moles of C–H bonds. So 330 kJ + 430 kJ + 3(410 kJ), or
1,990 kJ, of energy is released by bond making. The net change, which is
roughly equal to ∆H, is 1,880 kJ − 1,990 kJ = −110 kJ. Therefore, this
reaction is exothermic, and the correct answer is (E).