You accidentally dropped your favourite the and broke it . This is a change you did not want .Can this change be reversed ?

You accidentally dropped your favourite toy and broke it .This is a change you did not want.Can this change be reversed?

A drawing sheet changes when your draw a picture on it .Can you reverse this change ?

A drawing sheet changes when you draw a picture on it . Can you reverse this change ?

Read the following passage and answer the questions. Ultrafiltration is the process of separating the colloidal particles from the solvent and soluble solutes present in the colloidal solution by specially prepared filters, which are permeable to all substances except the colloidal particles. Colloidal particles can pass through ordinary filter paper because the pores are too large. However, the pores of filter paper can be reduced in size by impregnating with collodion solution to stop the flow of colloidal particles. The usual collodion is a 4% solution of nitrocellulose in a mixture of alcohol and ether. An ultra-filter paper may be prepared by soaking the filter paper in a collodion solution, hardening by formaldehyde and then finally drying it. Thus, by using ultra-filter paper, the colloidal particles are separated from rest of the materials. Ultrafiltration is a slow process. To speed up the process, pressure or suction is applied. The colloidal particles left on the ultra-filter paper are then stirred with fresh dispersion medium (solvent) to get a pure colloidal solution. How can you convert an ordinary filter paper into an ultrafilter paper ?

Read the following passage and answer the questions. Ultrafiltration is the process of separating the colloidal particles from the solvent and soluble solutes present in the colloidal solution by specially prepared filters, which are permeable to all substances except the colloidal particles. Colloidal particles can pass through ordinary filter paper because the pores are too large. However, the pores of filter paper can be reduced in size by impregnating with collodion solution to stop the flow of colloidal particles. The usual collodion is a 4% solution of nitrocellulose in a mixture of alcohol and ether. An ultra-filter paper may be prepared by soaking the filter paper in a collodion solution, hardening by formaldehyde and then finally drying it. Thus, by using ultra-filter paper, the colloidal particles are separated from rest of the materials. Ultrafiltration is a slow process. To speed up the process, pressure or suction is applied. The colloidal particles left on the ultra-filter paper are then stirred with fresh dispersion medium (solvent) to get a pure colloidal solution. How can you speed up the process of ultrafiltration ?

Can you suggest some changes in your school which could make it environment friendly?

Take a thick white sheet. Fold the paper once. Draw two line segments of different lengths as shown in the figure. Cut along the line segments and open up. You have the shape of a kite. Has the kite any line symmetry ? Fold both the diagonals of the kite. Use the set-square to check if they cut at right angles. Are the diagonals equal in length ? Verify (by paper-folding or measurement) if the diagonals bisect each other. By folding an angle of the kite. on its opposite check for angles of equal measure. Observe the diagonal folds, do they indicate any diagonal being an angle bisector ? Share your findings with others and list them. A summary of these results are given elsewhere in the chapter for your reference.

Take two identical pipes, as shown in Fig 12.23. You can make the pipe using chart paper. The length of the pipes should be sufficiently long as shown paper. Arrange them on a table near a wall. Keep a clock near the open end of one of the pipes, say pipe A and try to hear the sound of the clock through the other pipe. Put a playwood sheet between the two tubes perpendicular to the wall. This does not allow the direct hearing of the ticking sound of the clock. Ajust the position of the pipes so that you can best hear the sound of the clock. Now measure the angles of incidence and reflection and see the relationship between the angles.

Take two identical pipes, as shown in Fig 12.23. You can make the pipe using chart paper. The length of the pipes should be sufficiently long as shown paper. Arrange them on a table near a wall. Keep a clock near the open end of one of the pipes, say pipe A and try to hear the sound of the clock through the other pipe. Put a playwood sheet between the two tubes perpendicular to the wall. This does not allow the direct hearing of the ticking sound of the clock. Ajust the position of the pipes so that you can best hear the sound of the clock. Lift the pipe on the right vertically to a small height and observe what happens?