Question

Which of the compounds h2c2o4, ca(oh2, koh, and hi, behave as bases when they are dissolved in water?

Answer 1

H2C2O4, also written as (COOH)2, is Ethandioic acid, and, as evident by the name, is an acid, and not a base
Ca(OH)2 and KOH, Calcium Hydroxide and Potassium Hydroxide, respectively, are bases when dissolved in water, as they are able to release OH- ions.
Hydrogen Iodide, HI, when dissolved in water, is a strong acid. So, that is also not a base.

Answer 2

Answer: The correct answer is $Ca(OH)_2\text{ and }KOH$

Explanation:

Acids are defined as the chemical species that produces hydrogen ions on dissolving in water.

Bases are defined as the chemical species that produces hydroxide ions on dissolving in water.

We are given:

Chemical compounds having chemical formulas $CH_3COOH,Ca(OH)_2,KOH\text{ and }HI$

$CH_3COOH$ is an organic acid and it produces $CH_3COO^-\text{ and }H^+$ ions

$Ca(OH)_2$ is a base and it produces $Ca^{2+}\text{ and }OH^-$ ions

$KOH$ is a base and it produces $K^{+}\text{ and }OH^-$ ions

HI is an acid because it produces $H^+\text{ and }I^-$ ions

Hence, the correct answer is $Ca(OH)_2\text{ and }KOH$