Question

What happens when:
i. Boric acid is heated
ii. Boric acid is added to water
iii. Aluminium is treated with dilute $NaOH$

Answer 1

Boric acid, also known as hydrogen borate, boracic acid, and orthoboric acid, is a boron Lewis acid that is weak and monobasic. However, its behaviour toward certain chemical reactions suggests that it is also tribasic acid in the Bronsted sense.
When boric acid is heated it converts into metabolic acid which on further heating gives boron trioxide.
Boric acid takes electrons from the $-OH$ ion when it is introduced to water. Boric acid is very slightly soluble in cold water, but it is much more soluble in hot water. Boric acid has the properties of a mild monobasic acid.
Sodium tetrahydroxoaluminate is formed when Al interacts with dilute $NaOH{\text{ }}\left( {III} \right)$ . During the process, hydrogen gas is liberated.

Complete answer: Now, we will understand the process by equation:
Boric acid on heating forms a number of products depending upon the temperature . For example
${H_3}B{O_3}\xrightarrow{{370K}}HB{O_2} + {H_2}O \\\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,Metaboric\,acid \\\ 4HB{O_2}\xrightarrow{{410K}}{H_2}{B_4}{O_7} + {H_2}O \\\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,Tetraboric\,acid \\\ {H_2}{B_4}{O_7}\xrightarrow[{heat}]{{\operatorname{Re} d}}2{B_2}{O_3} + {H_2}O \\\$
ii. Boric acid receives electrons from the $-OH$ ion when it is introduced to water. Boric acid is very slightly soluble in cold water, but it is much more soluble in hot water.$B{\left( {OH} \right)_3} + 2{H_2}O \to {\left[ {B{{\left( {OH} \right)}_4}} \right]^ - } + {H_3}{O^ + }$
iii. Sodium tetrahydroxoaluminate is formed when $Al$ interacts with dilute $NaOH{\text{ }}(III)$ . During the process, hydrogen gas is liberated.
$2Al + 2NaOH + 6{H_2}O \to 2N{a^ + }{\left[ {Al{{\left( {OH} \right)}_4}} \right]^ - }\,\,\,\, + 3{H_2} \\\ \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,Sodium tetra hydroxy aluminate(III) \\\$

Note:
Boric acid is referred to as a swimming pool chemical since it has proven to be quite effective in the upkeep of swimming pools. It can help to keep the pH of water stable and prevent algal problems. The amount of chlorine required in the pool is reduced by using this product. The chemical can aid in the maintenance of clean, sparkling water. It's also used to get rid of fungus in swimming pool water.