Volume of a gas at STP is 1.12  ×  10−7  cc. Calculate the number of molecules in it

∵   22400  cc  of  gas  at STP has  6  ×  1023  molecules∴  1.12  ×  10−7  of  gas  at  STP has  6  ×  1023 × 1.12  × 10−7 22400                                                   =   3  ×  1012.