A teacher showed demonstration of action of acids on the metals in the laboratory. After the activity was over, one naughty student took an alluminium rod. He dipped it in a bottle containing concentrated nitric acid. Later, he dipped it in a beaker containing dilute `H_(2)SO_(4)` But, he did not find any bubbles coming out. He was surprised because he was able to see bubbles coming out when a metal rod is dipped in sulphuric acid when teacher did the experiment. He then approached the teacher and asked what is wrong with his activity. Predict the answer given by the teacher.

A teacher showed demonstration of action of acids on the metals in the

1.	A teacher showed demonstration of action of acids on the metals in the laboratory. After the activity was over, one naughty student took an alluminium rod. He dipped it in a bottle containing concentrated nitric acid. Later, he dipped it in a beaker containing dilute `H_(2)SO_(4)` But, he did not find any bubbles coming out. He was surprised because he was able to see bubbles coming out when a metal rod is dipped in sulphuric acid when teacher did the experiment. He then approached the teacher and asked what is wrong with his activity. Predict the answer given by the teacher.
Answer» `HNO_(3)` is highly corrosive in nature. As a result it forms an oxide layer on A1 rod which acts as a passive layer. This passive layer prevents the reaction between A1 and `H_(2)SO_(4)`. And hence no liberation of hydrogen gas.