Keep a glass full of water in the freezer for five to ten minutes . Then take it out and observe it carefully . From which part in the glass does water first start freezing ?

A ray of light travels from water to glass. Which one of the following statements is true ?

Apparatus : Test tube, beakers, burner, etc. Chemicals : Glacial ethanoic acid, ethanol, concentrated sulphuric acid, etc. Procedure : Take 1 mL ethanol and 1 mL glacial ethanoic acid in a test tube. Add a few drops of concentrated sulphuric acid in it. Keeps this test tube in the beaker containing hot water (hot water bath) for five minutes. Then take 20-30 mL water in another beaker, and pour the above reaction mixture in it and smell it. What can you say about the smell of the reaction mixture?

A glass bottle completely filled with water is kept in the freezer. Why does it crack? A. Bottle gets contracted B. Bottle is expanded C. Water expands on freezing D. Water contracts on freezing

Take two big glasses of water . Add 4-5 spoonfuls of salt to the water in one glass and dissolve it completely . Now place a potato in the water in the second glass . The potato will sink . Take out the potato from that glass and put it in the salt water and observe .

Take an empty can. Pour small quantity of water in it. Boil this water for a few minutes until the steam has driven out most of the air. Now close the can with the stopper tightly. Allow it to cool by pouring cold water over it. What do you observe ?

A ray of light travels from air to water to glass and again from glass to air. Refractive index of water with respect to air is ‘x’ glass with respect to water is ‘y’ and air with respect to glass is ‘z which one of the following is correct?

Search for a pond with greenish water. Collect some of the green fibres from the water. Put the fibres in a petridish and wash them clean with water. Put one of the fibres in a drop of water on a glass slide and spread it out straight. Put a cover-slip over the slide and observe under a compound microscope.

Try this. Take a suitable glass vessel like conical flask or beaker.Add some garden soil in it and sow some pulse grains in it in such away that you can observe them through glass. Water it every day and record the changes.

Apparatus: Two plastic bottles, measuring cylinder, thermometer, etc Chemicals: Potassium nitrate, sodium hydroxide, water, etc. (Sodium hydroxide being corrosive, handle it carefully in presence of teacher.) Procedure: Take I 00 mL water in each of the two plastic bottles. Plastic being insulator of heat, the dissipation of heat can be prevented. Note the temperature of water in the bottles. Put 5 g potassium nitrate (KNO_3) in the bottle and shake well. Note the temperature of the solution formed. Put 5 g sodium hydroxide (NaOH) in the other bottle. Shake the bottle well. Note the temperature. In the first bottle, the process of dissolution of potassium nitrate took place while in the second bottle, the process of dissolution of sodium hydroxide took place As per your observation which one is exothermic process and which is an endothermic process?

Activity 1 : Take a conical flask and collect the water in it from a pond having stagnent water and aquatic plants. Add some wheat grans and aquatic plants to it. Keep it for 3-4 days so that wheat grains and plants will decompose. Early in the morning on fourth day, take a glass slide and put a drop of that water over it. Carefully, put a cover-slip on that drop and observe under compound microscope.