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Question:

Among the following, the number of compounds that can react with PCl5 to give POCl3 is: O2, CO2, SO2, H2O, H2SO4, P4O10

6

5

3

4

Solution:

PCl5 reacts with four of the given compounds to produce POCl3. The reactions are:

  1. PCl5 + H2O → POCl3 + 2HCl
  2. PCl5 + SO2 → POCl3 + SOCl2 (Thionyl chloride)
  3. PCl5 + H2SO4 → POCl3 + SO2Cl2 + HCl
  4. 6PCl5 + P4O10 → 10POCl3

CO2 and O2 do not react with PCl5 to form POCl3. Therefore, the correct answer is 4.