Question

What is the colour change for china rose treated with lime juice
(A). Colour changes to magenta
(B). Colour changes to red
(C). Colour changes to green
(D). No effect

Answer 1

In nature with the existence of positive side negative side also exists. Iff acids are found in nature then bases are also there. For the confirmation of presence of acids or bases we need some materials named as neutral indicators. They are called indicators because they indicate the presence of acids or bases in a mixture.

Complete answer:
Acids and bases are derived from Greek language which means sour and bitter. Acids on reaction with base gives neutral compounds like water. However, the confirmation is done by the indicators only.
Several indicators are there in nature like china rose, litmus paper, turmeric and many more.
Let us now discuss our case of china rose. When acid is dropped over china rose it turns deep pink or magenta in colour and when base is dropped on the china rose it turns green. Thus the correct option is (A). Colour changes to magenta. The reaction is as given below: -
$Green\,colour\xleftarrow{{base}}China\,Rose\xrightarrow{{acid}}Meganta\,(deep\,pink)\,colour$
With the help of indicators we can separate the acids or the bases as well.

Note:
Indicators give different colours when they come in contact with acid and base. Acid when dropped on litmus will give red colour, whereas when base is added it turns blue. Similarly when base is added to turmeric it gives red colour whereas when acid is poured to turmeric it gives no characteristic colour.