Light — Science STD 7 — Question

A vehicle moves along a straight line and covers a distance of 2 km. In the first 500 m, it moves with a speed of 10 m/s and in the next 500 m, it moves with a speed of 5 m/s. With what speed should it move the remaining distance so that the journey is complete in 200 s? What is the average speed of the vehicle for the entire journey?

Mention one way of overcoming the problem of the lack of sewage systems in villages.

Write the factors which affect the climate of a particular place.

Define oral rehydration solution and when is it given to the patient? How can you prepare ORS at home?

State the factors on which amount of heat produced depends?

What are the functions of ribs and diaphragm during breathing? Describe their functioning.

Why chemical changes are very important in our life?

Briefly explain the following:
(a) Periscope
(b) Kaleidoscope
Also, mention two applications of each.

Arrange the following statements in the correct order in which they occur during the formation and removal of urine in human beings.

1. Ureters carry urine to the urinary bladder.
2. Wastes dissolved in water is filtered out as urine in the kidneys.
3. Urine stored in urinary bladder is passed out through the urinary opening at the end of the urethra.
4. Blood containing useful and harmful substances reaches the kidneys for filtration.
5. Useful substances are absorbed back into the blood.

Is air essential for combustion? Explain with the help of an activity.