Question

What colour do the following indicators turn when added to a base or alkali (such as sodium hydroxide) ?
(a) methyl orange
(b) litmus
(c) red cabbage extract

Lakhmir Singh Chemistry Class 10

Answer 1

Explanation:

Indicators are the species or substances which change color when there is change in pH of the solution.

For example, phenolpthalein, methy orange etc are indicators.

Indicators are used in acid-base titrations to find the point of neutralization of an acid or base.  

when added to a base or alkali, the color of given indicators turn as follows

• Methyl orange changes color from orange to yellow.
• Litmus changes color from red to blue.
• Red cabbage extract changes color from blue to green to yellow.  

Answer 2

Explanation:

Litmus - when base added then changes red to blue

phenolphthalein - base -pink

china rose - deep pink (asid) and green color (base)

turmeric - red (base)

red cabbage extract - bluish green