Alka was making tea in a kettle. Suddenly she felt intense heat from the puff of stream gushing out of the spout of the kettle. She woundered whether the temperature of the stream was higher than that of the water boiling in the kettle . Comment.

Raman is a student of class X. Raman's mother was making tea in an old electric kettle having metal case. She switched on the power supply to the electric kettle. When Raman's mother touched the metal case of working electric kettle unknowingly, she got a severe electric shock. Raman put off the main switch quickly. After removing the kettle plug from socket, Raman found that the connecting cord was torn where it touched the metal case of the kettle. He also found that though the red and black wires of connecting cord were firmly connected to the two lower terminals of the power plug but the green wire of cord was not connected to the upper terminal of the plug. Raman replaced the torn connecting cord and also connected the three wires fo cord firmly to the power plug terminals. (a) Why did Raman put off the main switch quickly ? (b) What name is given to (i) red wire (ii) black wire, and (iii) green wire, of the connecting cord ? (c) Which wire, red, black or green, touched the metal case of electric kettle when Raman's mother got electric shock ? (d) Which safety device was not working in electric kettle circuit which could have prevented the electric shock ? (e) What values are displayed by Raman in this incident ?

Paheli kept some water in a beaker for heating. She observed that tiny bubbles appeared before the water started to boil. She boiled the water for about 5 minutes and filled it in a bottle up to the brim and kept the bottle air tight till it cooled down to room temperature (a) Why did the tiny bubbles appeared ? (b) Do you think tiny bubbles will appear on heating the water taken out from the bottle? Justify your answer.