Question

What are the properties of acid?
A) That is capable of donating ${H^ + }$
B) That has lower pH
C) $HCl$ is an acid
D) All of the above

Answer 1

We must have to remember that it is easy to identify a base and an acid. As we know, a base usually contains a hydroxide ion and an acid contains ${H^ + }$ ion. Acid can turn blue litmus red and it is sour in taste.

Complete answer:
Option A) this option can be correct as acid is an ion or molecule which is capable of donating a proton. These proton donors form Hydronium ions and are known as Arrhenius acid.
We need to remember that according to Arrhenius concept, an acid when dissolved in water releases ${H^ + }$ since when an Arrhenius acid releases ${H^ + }$, ${H_2}O$ molecule accept it forming Hydronium ion(${H_3}{O^ + }$)
${H_2}O + {H^ + } \to {H_3}{O^ + }$
Option B) This option can be correct as acid has lower $pH$. The value of $pH$ in acid is below $7$, as $pH$ =7 is neutral and $pH$ above 7 is a base.
Option C) this option can be correct as $HCl$ is an acid.
$HCl$is a strong acid which can also be known as Arrhenius acid.
On making an aqueous solution of$HCl$, it dissociates itself into ${H^ + }$ and $C{l^ - }$ ions.
$HCl \to {H^ + } + C{l^ - }$
We need to know that as the concentration of ${H^ + }$ increases in the solution, thus $HCl$is an Arrhenius acid.
Option D) this option is correct as all the options given above are correct.

Note:
Sometimes, when an Arrhenius base reacts with an Arrhenius acid the products so formed are water and a salt, this type of reaction may be called as Neutralization reaction. Also, Arrhenius theory is limited to acid-base chemistry only.