Task: Question Answering
Input (English): Question: If we try to dissolve ammonia in water we observe that: 
 Options:  <1> It is completely soluble. <2> It is not very soluble. <3> It should be poorly soluble, but the solubility increases markedly by acid-base reaction between them, resulting in an acid solution. <4> It should be poorly soluble, but the solubility increases markedly by redox reaction between them, releasing hydrogen. <5> It is very soluble, favored by the formation of hydrogen bonds between the two compounds.
Output (English): 5