1. Calculation of the mass of NaCl needed to prepare 250 cm³ of a 0.200 mol/dm³ NaCl solution. 2. Explanation of the weighing by difference method for accurately transferring NaCl into a beaker. 3. Detailed procedure for preparing the NaCl solution and the apparatus required for the preparation. 4. Suggesting an improvement to the experimental method, calculating the percentage error in volume measurements, and ensuring the reliability of the results. 5. Analysis of experimental data to determine the molar ratio of NaCl and lead compound in a precipitation reaction. 6. Explanation of how various experimental factors, such as longer burning of the spirit burner or delayed lid replacement, could affect the accuracy of the experiment. 7. Suggestions for improving the experimental procedure to obtain the expected results in a reaction involving sodium hydroxide and halogenoalkanes.