You should never taste anything in a lab. Litmus paper will only tell you whether it is an acid or a base, not how strong it is a hydrogen test only works with acids. You can get a serious burn from touching strong acids and bases and it doesn't give an objective measure of the strength. The only one that is left is conductivity. This is safe and rather reliable, because the "strength" of an acid or a base depends on how much it dissociates. Hence more dissociation means greater conductivity.
I think the correct answer from the choices listed above is option A. The fact that we know about the relationship between the hotter water and the cooler water would be that the <span> hotter water is less dense. Hope this answers the question. Have a nice day.</span>
