NH4Cl has the greatest solubility in 100 grams of water at 10°C. The correct option is 4.
The compound with the greatest solubility in 100 grams of water at 10°C can be determined by referring to Table G. From the given options, we need to find the compound that has the highest solubility in water. Based on the information provided, HCl, NaCl, KCl, and NH4Cl are the compounds to consider.
According to Table G, the solubility of HCl is 82 g per 100 g of water at 10°C, NaCl is 35.7 g/100 g H2O, KCl is 34.2 g/100 g H2O, and NH4Cl is 37.2 g/100 g H2O.
Therefore, NH4Cl has the greatest solubility in 100 grams of water at 10°C.