Which of the following substances can act as a Brønsted-Lowry base?

a) HClO4(aq)
b) HOCl(aq)
c) H2O(l)
d) H3O+(aq)
e) none of the above

b) HOCl(aq)

c) H2O(l)
d) H3O+(aq)

In the Brønsted-Lowry definition of acids and bases, a base is a substance that can accept a proton (H+ ion) from an acid.
HOCl and H2O can both accept protons to form their conjugate acids.
Similarly, H3O+ is the hydronium ion and it can accept a proton to form a more acidic species.

HClO4 is an acid, not a base, as it donates a proton (H+) to form its conjugate base.
So the correct answer is e) none of the above.

are you sure?

Apologies for the confusion. You are correct, I made an error in my previous response. Let's reassess the options:

a) HClO4(aq) - HClO4 is a strong acid, so it acts as an acid rather than a base.
b) HOCl(aq) - HOCl is a weak acid, but it can still function as a weak base and accept a proton.
c) H2O(l) - Water can function as both an acid and a base, so it can act as a Brønsted-Lowry base.
d) H3O+(aq) - H3O+ is an oxonium or hydronium ion, which is the conjugate acid of water. It can also function as an acid rather than a base.

So, the correct answer is b) HOCl(aq), c) H2O(l), and d) H3O+(aq).

What is the correct answer?

Apologies for the confusion again. The correct answer is:

b) HOCl(aq)
c) H2O(l)

Both HOCl and H2O can act as Brønsted-Lowry bases by accepting a proton from an acid.

To determine which of the following substances can act as a Brønsted-Lowry base, we need to understand the definition of a Brønsted-Lowry base.

According to the Brønsted-Lowry theory, a base is a substance that can accept a proton (H+) from another substance.

Let's analyze each option:

a) HClO4 (hydrochloric acid) is a strong acid, but it can still act as a base by accepting a proton from another substance. Therefore, it can act as a Brønsted-Lowry base.

b) HOCl (hypochlorous acid) is a weak acid and can also act as a base by accepting a proton from another substance. So, it can be considered a Brønsted-Lowry base.

c) H2O (water) can act as an acid by donating a proton, but it can also act as a base by accepting a proton from another substance. Hence, water can be considered a Brønsted-Lowry base.

d) H3O+ (hydronium ion) is formed when an acid donates a proton to water. It is a strong acid, but it can still act as a base by accepting a proton from another substance. Therefore, it can act as a Brønsted-Lowry base.

Based on the analysis above, all options a), b), c), and d) can act as Brønsted-Lowry bases. Therefore, the correct answer is e) none of the above.