What is the aim of the experiment, the purpose of cleaning the leaf, and the role of sellotape? Also, what is the original color of dry cobalt(II) chloride paper, what color change did students observ

Here are the answers to your questions:

a)

i) The aim of the experiment was to investigate the rate of transpiration from the upper and lower surfaces of a leaf.

ii) The purpose of cleaning the leaf was to remove any dust or dirt particles that might block the stomata or interfere with the experiment's results.

iii) The role of sellotape (cellotape) in this experiment was to hold the cobalt(II) chloride paper firmly in place on the leaf surfaces and to prevent external moisture from affecting the paper.

b)

i) The original colour of dry cobalt(II) chloride paper is blue.

ii) Students observed a colour change from blue to pink.

iii) The difference in time taken for the colour change is due to the uneven distribution of stomata on the leaf surfaces. The lower epidermis typically has a higher concentration of stomata than the upper epidermis. Stomata are pores through which water vapour is released during transpiration. Therefore, more water vapour is released from the lower surface, causing the cobalt(II) chloride paper to change colour faster (in 2 minutes) compared to the upper surface (5 minutes).