Why is mass conserved in a chemical change?
the energy used in the chemical reaction burns up the extra matter.
the compounds are still exactly the same, they just look different.
the atoms are still there, they are just rearranged to form new compounds
the new matter that is formed takes up the same volume as the original matter.

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.