Question

An experiment is set up as shown. Test tube (i) contains a solution of potassium hydroxide. Test tube (ii) and (iii) contain freshly prepared limewater. A conical flask between (ii) and (iii) contains germinating seeds. Air is blown into the set up through pipe X. What do you think will be the appearance of limewater in test tubes (ii) and (iii) after some time?

Option	Test tube (ii)	Test tube (iii)
A.	No change is seen in limewater.	No change is seen in limewater.
B.	Limewater turns milky.	No change is seen in limewater.
C.	No change is seen in limewater.	Limewater turns milky.
D.	Limewater turns milky.	Limewater turns milky.

[0.8 Mark]

• A. A
• B. B
• C. C
• D. D

Answer 1

The correct option is C C

We know that potassium hydroxide absorbs carbon dioxide. So, when air is blown by the boy inside the test tube (i), all the carbon dioxide gets absorbed. As a result, no carbon dioxide passes to test tube (ii) which contains limewater. Hence, the limewater does not turn milky. The flask between the test tube (ii) and test tube (iii) contains germinating seeds. These seeds respire, and release carbon dioxide. This carbon dioxide then enters test tube (iii) containing limewater and turns it milky.