Collect the following samples from the science laboratory hydrochloric acid (HC), sulphuric acid (H,SO,), nitric acid (HNO,). acetic acid (CH,COOH), sodium hydroxide (NaOH), calcium hydroxide [Ca(OH),], magnesium hydroxide [Mg(OH),J,ammonium hydroxide (NH,OH) and potassium hydroxide (KOH), prepare dilute solutions of the respective substances

Take four watch glasses and put one drop of the first solution in each one of them and test the solution as follows.

1. dip the blue litmus paper in the first watch glass
2. dip the red litmus paper in the second watch glass.
3. add a drop of methyle organge to the third watch glass, and
4. add a drop of phenolphthalein to the fourth watch glass

Observe the respective colour changes and note down in Table-1. Do the same with all the above dilute solutions.

• What do you conclude from the observations noted in table-1?
• Identify the sample as acidic or basic solution.

There are some substances whose odour changes in acidic or basic media. These are called olfactory indicators Let us work with some of such indicators.