In an experiment, onion plants of different ages were exposed to various amounts of caffeine to determine the effect of caffeine on cell growth. temperature, amount of water, and light were kept constant. which of these statements about the experiment is definitely true?
a. the results may not be valid because there were two variables.
b. the amount of caffeine used was a control.
c. temperature, water, and light were the only variables.
d. onion plants can be used to model the effects of caffeine on living things.

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).

the correct answer is b. a strong acid completely dissociates to its ions when dissolved in water. completely dissociates to and ions. a is incorrect because does not fully ionize to and ions and some remain as the compound . c and d are incorrect because, and do not fall into the category of bronsted lowry acids. a bronsted lowry acid is a proton donor and since both molecules do not have a proton to donate they are not bronsted lowry acids. likewise,   if we use the lewis acid definition, they cannot be acids. a lewis acid is an electron pair acceptor. both and have a complete octet so can not accept any electrons which disqualifies them as acids.