Fibre to Fabric — Science STD 7 — Question

Explain neutralisation reaction with the help of an example, which indicator is used in this process.

The method of transfer of heat, i.e. convection is only possible in fluids. Explain why?

Compare the temperatures of two thermometers having black and white bulbs under sunlight by drawing table and state reason behind the result.

A food stall owner was preparing dough for making bhaturas. He added a pinch of yeast and sugar to the dough and left it in a warm place. After few hours, the dough had risen. There was a sour smell too. What would have happened if the dough was kept in the refrigerator, soon after it was prepared?

Give an example of a chemical reaction for each of the following situation: A change in colour is observed.

Explain how Galileo contributed to the development of clocks.

To test the presence of an acid in any substance, what methods can be used?

Given below is a model showing mechanism of breathing?

(a) Did you see any changes in the balloons?
(b) What do the balloons in this model represent?
(c) What does the rubber sheet represent?

State any two observations from everyday life which show that light travels in straight lines.

Distinguish between a parasite and a saprotroph.