Two test-tubes, P and Q, were prepared, and each one contained a solution of red hydrogencarbonate indicator. Hydrogencarbonate indicator becomes yellow when the carbon dioxide concentration rises and turns purple when the carbon dioxide concentration falls. Matching pieces of the same aquatic plant were put into tubes P and Q. Tube P was left uncovered, whereas tube Q was covered with a black light-proof cover. The tubes were then kept in a warm room in sunlight for four hours. What colour would the hydrogencarbonate indicator be in the two tubes after four hours?
- Atube P: purple; tube Q: red
- Btube P: purple; tube Q: yellow
- Ctube P: red; tube Q: yellow
- Dtube P: yellow; tube Q: red