Given answer of some cpt exam june-2010 qusation

Hello, everybody

      please given me answer of  some cpt exam june-2010  qusation following are qusation  and please given correct answer of follwing qusation

   1)  If the price of goods is 180 and consumer willing to purchsed goods from Rs- 320 in case what is the consumer surplus ?

             A)  500   B) 140  C) 180   D) None of these

 2)  When there are 10 quantity of goods the price of 200 and when there are 20 quantity of goods the price is 600 then what will of marginal cost of the goods ?

           A) 200   B) 40  c) 400  D) None of these

 3) In contraction and expansion demand will be ?

         A) Demand is unchanged  B) Demand is changed   C) Slope of demand changed  D) None