Questions

Write the full forms of DDT and BHC.

Pickles can be preserved for a long time. Give reason.

Give reason: Salt is used in the process of making soap.

Give reason: The use of chemical pesticides should be decreased.

Give reason: The use of DDT powder causes imbalance in the ecosystem.

Write differences between Soap and detergent.

Write differences between Chemical food preservative and organic food preservative.

Write differences between Chemical pesticides and biological pesticides

The monthly consumption of electricity (in units) of 50 consumers is given in the table below.

1. Write the formula to find the median of a continuous series.
2. Find the modal class and median class of the given data.
3. Calculate the median of the given data.
4. Did you find the modal class and median class same from the above computation? Are they always same? Give reason.

In the given figure, AB is the height of a boy, and a point C is the position of a flying kite in
the sky. AC is the length of the string of the kite.

1. Define angle of elevation
2. If $\angle$CAH =30$^{\circ}$, what is the value of CH? Find it.
3. Find the height of the kite flying in the sky.
4. If the measure of $\angle$CAH be changed from 30$^{\circ}$ to 45$^{\circ}$, at what height the kite fly than the previous height ? Find it.