NEET BIOLOGY

Detailed explanation-1: -Hydrogencarbonate indicator can detect increases and decreases in carbon dioxide concentration. It is normally red. However, an increase in carbon dioxide changes the indicator to yellow and a decrease in carbon dioxide changes it to purple.

Detailed explanation-2: -Hydrogencarbonate indicator (HCI) is a pH indicator which can be used to measure the concentration of carbon dioxide over a range of pH values. HCI is orange/red in equilibrium with air and becomes increasingly yellow as the concentration of CO2 increases (the solution becomes more acidic).

Detailed explanation-3: -Bicarbonate indicator is used to show the presence of carbon dioxide. The gas changes the colour of the bicarbonate indicator from red to yellow.

Detailed explanation-4: -Bromothymol blue (BMB) is an indicator dye that turns yellow in the presence of acid. When carbon dioxide is added to the solution, it creates carbonic acid, lowering the pH of the solution. BMB is blue when the pH is greater than 7.6, green when the pH is between 6-7.6, and yellow when the pH is less than 6.

Detailed explanation-5: -When the carbon dioxide content is higher than 0.04%, the initial red colour changes to yellow as the pH becomes more acidic. If the carbon dioxide content is lower than 0.04%, it changes from red to magenta and, in relatively very low carbon dioxide concentrations, to purple.