$5.$ At acidic pH values, methyl red $($HMR$)$ is color red, while at basic pH values, its basic

counterpart MR$-$ is color yellow.

HMR$($aq$)+$ H$2$ O$($l$)$ H$3$ O$+($aq$)+$ MR$-($aq$)$

When NaOH is added to a methyl red solution, to which species does it react?

a$.$ HMR

b$.$ H$2$ O

c$.$ H$3$ O$+$

d$.$ MR$-$

$16.$ Which of the following statements is TRUE regarding colligative properties of solutions?

a$.$ Kf and Kb are constants that depend on the nature of the solute.

b$.$ An aqueous solution of NaCl has a lower freezing point than an equimolal aqueous

MgCl$2.$

c$.$ The magnitude of boiling point elevation is always the same as the freezing point

depression.

d$.$ The van$$t Hoff factor of a solute is always equal to the number of ions of solute in an

ideally dilute solution

$20.$ What is the final $[$OH$-]$ if a $25\mathrm{.}0$ mL solution of pH $4\mathrm{.}67$ were to be diluted to $100\mathrm{.}0$ mL$?$

a$.5\mathrm{.}37\backslash$times $10^-6$

b$.1\mathrm{.}87\backslash$times $10^5$

c$.1\mathrm{.}87\backslash$times $10^-9$

d$.5\mathrm{.}37\backslash$times $10^8$

$22.$ In the reaction between sodium carbonate and acetic acid, what does the evolution of gas

imply about the involved species?

a$.$ Carbonate is a stronger base than acetate.

b$.$ Carbonic acid is a stronger acid than acetic acid.

c$.$ The proton is transferred from carbonic acid to acetate.

d$.$ The proton is transferred from carbonate to acetic acid.

$23.$ Based on the reactions below, what is the correct order of the basic species according to

increasing basic strength?

CH$3$ NH$2+$ HCl $->$ CH$3$ NH$3++$ Cl$-$

HCl $+$ CO$32-->$ Cl$-+$ CO$2+$ H$2$ O

H$2$ CO$3+$ CH$3$ NH$2->$ No reaction

a$.$ CH$3$ NH$3+<$ H$2$ CO$3<$ HCl

b$.$ H$2$ CO$3<$ CH$3$ NH$3+<$ HCl

c$.$ CO$32-<$ CH$3$ NH$2<$ Cl$-$

d$.$ Cl$-<$ CH$3$ NH$2<$ CO$32-$