Choose the correct answer for each question.

1. 4.35 g of potassium sulphate, K2SO4, is dissolved in water and made up to 100 cm3. What is the concentration of potassium ions in mol dm-3?
   

   1.   ?    0.025
   2.   ?    0.050
   3.   ?    0.250
   4.   ?    0.500

2. 0.4 g of an oxide of metal X reacts completely with 0.01 mole of aqueous nitric acid according to the equation:
   XO    +    2HNO3   =    X(NO3)2    +    H2O
   The relative atomic mass of metal X is
   

   1.   ?    24
   2.   ?    40
   3.   ?    64
   4.   ?    80

3. If 8.7 g of potassium sulphate is dissolved in water and made up to 200 cm3, what is the concentration of the solution in mol dm-3?
   

   1.   ?    0.05
   2.   ?    0.20
   3.   ?    0.25
   4.   ?    0.50

4. 25 cm3 of potassium iodate (V) solution were added to excess potassium iodide solution dissolved in sulphuric acid. The iodine liberated required 30 cm3 of 0.50 M Na2S2O3.
   Which one of the following is the concentration of the potassium iodate solution?
   

   1.   ?    0.1 M
   2.   ?    0.2 M
   3.   ?    0.4 M
   4.   ?    0.5 M

5. Which one of the following is the correct equation for the reaction between iodine and sodium thiosulphate?
   

   1.   ?    I2    +    S2O32-    =    2I-    +   S4O62-
   2.   ?    I2    +   2S2O32-    =    2I-    +    S4O62-
   3.   ?    I2    +    SO42-   =   2I-   +    S2O82-
   4.   ?    I2    +    2SO42-    =   2I-   +    S2O82-

6. Which one of the following are the names of the reagent and the indicator used in an iodine titration?
   

   1.   ?    sodium sulphate and starch
   2.   ?    sodium sulphate and methyl orange
   3.   ?    sodium thiosulphate and starch
   4.   ?    sodium thiosulphate and methyl orange

7. The presence of iodine can best be detected by

   1.   ?    universal indicator
   2.   ?    silver nitrate solution
   3.   ?    starch
   4.   ?    methyl orange