Question: Ammonia usually used in the laboratory: 
 Options:  <1> It is a pure compound, liquid at environmental temperature and pressure. <2> It is a gaseous ammonia solution in water, very diluted, because ammonia is very little soluble in water. <3> It is a solution of gaseous ammonia in water, very concentrated, because ammonia is very soluble in water. <4> It is a gaseous ammonia solution in ethanol, because pure gaseous ammonia is insoluble in water. <5> It is a saturated solution of ammonium chloride in water.
3