) NH3 and water are polar substances, while N2 and H2 are nonpolar substances. According to the principle of similarity compatibility, NH3 is soluble in water, N2 and H2 are insoluble in water, and NH3 can form intermolecular hydrogen bonds with water, so NH3 is extremely soluble in water.

(2) The boiling point of 2)HBr is higher than that of HCl because its molecular weight is higher than that of HCl, so its Van der Waals force is higher than that of HCl, so its boiling point is higher than that of HCl; The boiling point of HBr is lower than that of HF because the F atom of HF is very electronegative and hydrogen bonds can be formed between HF molecules, so the boiling point is higher than that of HBr.

(3) This still needs to consider the van der Waals force between them. Generally, in the absence of hydrogen bonds, the larger the molecular weight, the greater the intermolecular force and the higher the boiling point. (mainly related to the dispersion of van der Waals force. Too much trouble. Just look at the textbook. )

Van der Waals force is closely related to molecular polarity. Generally speaking, the greater the molecular polarity, the greater the van der Waals force and the greater the SARS.