Pick the odd-one-out from the group given below on the basis of respiratory organ. Give a reason for your answer.

Snake, tadpole, crow, goat.

On an average, an adult human being at rest breathes $15-18$ times per minute. The breathing rate, however, may differ under different conditions. Arrange the following activities given in the box in order of increasing breathing rates and give a reason for your answer.

[Sleeping, cycling, brisk walk, watching TV]

Paheli participated in a $400 \mathrm{m}$ race competition held at her school and won the race. When she came home, she had mixed feelings of joy and pain as she had cramps in her leg muscles. After a massage, she was relieved of the pain. Answer the following question related to the situation.

What can be the possible reasons for the pain in her legs?

Paheli participated in a $400 \mathrm{m}$ race competition held at her school and won the race. When she came home, she had mixed feelings of joy and pain as she had cramps in her leg muscles. After a massage, she was relieved of the pain. Answer the following question related to the situation.

Why did she feel comfortable after a massage?

Observe figure carefully and answer the following.

In which jar, will the amount of ${\mathrm{CO}}_2$ be the highest and why?