Answer:
The technique is called weighing by difference
Tops stops spinning because it doesn't have energy or ran out of force for example when you spin a top you give force to it then after 30 sec it going to stop going slower and slower that Is losing energy that's how tops stops spinning
Answer:
1M HCl: add 1mol/12M = 83 ml conc. HCl to 1L of water or 8.3ml to 100ml.
2M HCl: add 2mol/12M = 167 ml conc. HCl to 1L of water or 16.7ml to 100ml.
Cl2 is nonpolar so it has to be only London dispersion force (LDF)