The acid that contains a comparatively lesser amount of water is called concentrated acid. Different concentrated acids such as a concentrated hydrochloric acid (HCI), concentrated sulfuric acid (H2SO4), concentrated nitric acid (HNO3) etc. are used in laboratories at different times. If these acids come in contact with our body parts, they will create injury on those spots. For this reason, when using these acids, we need to put on hand gloves, goggles, mask, apron etc. for cautions.
Concentrated Hydrochloric Acid (Conc. HCl):
The solution that is produced when hydrogen chloride gas is dissolved in water is hydrochloric acid. In this solution, the amount of water is comparatively lesser than the amount of hydrogen chloride gas.
The moment when the cork of the container bottle of concentrated HCl is opened, there is a fog created and a highly pungent smell spreads all over. For this reason, before opening the bottle of concentrated HCl, nose and mouth should be covered in mask and eyes should be protected with goggles.
Concentrated Nitric Acid (Conc. HNO3):
The solution that is produced when nitrogen dioxide gas is dissolved in water is called nitric acid. To prepare nitric acid (HNO3) comparatively higher amount of NO2 gas is dissolved in a small amount of water (H2O). 
The moment when the cork of the container bottle of concentrated HNO3 is opened, there appears a fog and a highly pungent smell spread all over.
The colour of the container bottle of nitric acid is brown to prevent light to enter the bottle. If light enters the bottle, the HNO3 will be decomposed.
Concentrated Sulfuric Acid (Conc. H2SO4):
The solution that is produced when sulfur dioxide gas is dissolved in water is called sulfuric acid. To prepare sulfuric acid (H2SO4) comparatively higher amount of SO2 gas is dissolved in a small amount of water (H2O). 
