Solid NaOH is hygroscopic, meaning it absorbs moisture from the air. A student places solid NaOH into a weighing dish and leaves the sample out for too long before weighing it$.$ The student then dissolves the NaOH and uses the solution in a titration of an acid. The measured amount of the acid will therefore be

A$.$ less than the actual amount of acid

B$.$ greater than the actual amount of acid

C$.$ equal to the actual amount of acid

D$.$ the answer cannot be determined with the given information

An acid, HA$,$ has an acid dissociation constant of $7^{**}{10}^{-3}.$ Which of the following is the expected $pH$ of a solution that contains equal concentrations of $HA$ and $A^{-}($the conjugate base of $HA)?$

A$.1\mathrm{.}8$

B$.2\mathrm{.}2$

C$.3\mathrm{.}7$

D$.4\mathrm{.}9$

An acid is titrated with a sodium hydroxide and a titration curve is developed. The half$-$equivalence point is found to be at a $pH$ of approximately $4$ and the equivalence point is found to be at a $pH$ of approximately $8.$ What is the Ka of this acid?

A$.{10}^{-3}$

B$.9{10}^{-5}$

C$.1\mathrm{.}2{10}^{-8}$

D$.9{10}^{-10}$

If $0\mathrm{.}025L$ of a $4M$ solution of sodium hydroxide is titrated with hydrochloric acid, how many millimoles of hydrochloric acid would be expected to be used in the reaction?

A$.100$

B$.10$

C$.16$

D$.6$