Match the following :

	A		B
i.	red cabbage leaves	a.	olfactory indicator
ii.	methyl orange	b.	acid base indictor
iii.	Onion, clove	c.	natural acid base indictor

The correct answer is '(i) - (c), (ii) - (b), (iii) - (a)'.

Key Points Red cabbage leaves:

• Red cabbage indicator is a purple-coloured solution that is used to test whether substances are acid or base.
• Red cabbage that is often found in homes can be used to prepare a solution that acts as a natural pH indicator.
• The cabbage basically contains a pigment molecule called flavin or anthocyanin that changes colour depending on the acidity of the solution.

Methyl orange:

• Methyl orange is used as an indicator. It shows colour changes in acid, base and neutral substance.
• Methyl orange is a weak base.
• Methyl orange indicator is used in the strong acid weak base titration.
• The colour change of methyl orange depends upon the pH of the solution.
• In acidic medium means pH below 3.0 it shows red colour.
• In the range 3.0 - 4.5 pH, Methyl orange is of orange colour and in basic medium shows yellow colour.

Onion, clove:

• Vanilla, clove and onion are olfactory indicators.
• An olfactory indicator is a substance whose smell varies depending on whether it is mixed with an acidic or a basic solution.

Hence the table should be :