Answer
a) There is no difference if the tax was imposed on producers or consumers.
b) The more effective the tax would be in decreasing the quantity of gas consumed.
c) Consumers of gas are hurt by the tax.
d) Oil industry workers are hurt by the tax.
Work Step by Step
a) If the tax was imposed on producers, then the supply curve (in the first graph) would shift from $S$ to $S_{1}$. The equilibrium price and quantity would decrease and decrease, respectively. (The price consumers pay would be $P_{2}$, but the price firms would receive is $P_{2}-.50$.)
If the tax was imposed on consumers, the demand curve (in the first graph) would shift from $D$ to $D_{1}$. The equilibrium price and quantity would decrease and decrease, respectively. Thus, it would not matter if the tax was imposed on producers or consumers.
b) In the second graph, $D_{1}$ is the more elastic demand curve, and $D_{2}$ is the more inelastic demand curve. With a very inelastic demand curve (such as $D_{2}$), the quantity demanded would decrease somewhat (from the initial equilibrium quantity).
With a very elastic demand curve (such as $D_{1}$), the quantity demanded would decrease more than with an inelastic demand curve (compared to the initial equilibrium quantity).
c) With the tax added to the gas price, the quantity of gas demanded would be less than the equilibrium, and the price of the gas would be increased.
d) The demand for gas would be decreased, so there would be a demand for fewer oil industry workers.
