Forests: Our Lifeline — Science STD 7 — Question

Why is it necessary to excrete waste products?

We excrete more yellowish urine during the summers as compared to the winters give reason.

What is sludge? Explain how it is treated.

Explain sea breeze.

Identify whether the given materials are good or poor conductors of heat.

Material	Good or Poor conductor of heat

Describe the process of neutralization with the help of an example.

Why does an athlete breathe faster and deeper than usual after finishing the race?

Radhika wanted to buy a silk frock and went to the market with her mother. There they found that the artificial (synthetic) silk was much cheaper and wanted to know why? Do you know why? Find out.

During a science experiment, a student sets up a simple pendulum in the lab. She observes that the pendulum completes 40 complete oscillations in 80 seconds.
(i) Calculate the time period of the pendulum.
(ii) If the number of oscillations is doubled, but the total time also becomes double, will the time period change? Explain.

Describe in detail about the occurrence of oceanic currents.