Selvi took a conical flask, put some ice cubes into it and closed it with a stopper. Then, she found the weight of the conical flask using a balance. Its weight was 150 g. After some time, ice started melting and turned into water. She weighed the flask again. The weight was 150 g. What inference would you draw from this experiment?

a) What happens in the discharge tube if a high voltage is applied at a gas pressure of 760 mm mercury?

b) What will happen if the pressure is reduced to 0.01mm of mercury?

How can we prove that the electrons carry a negative charge?

Kannagi, Goutam, David, and Saleem collected different samples of water from a well, a pond, a river and underground water. All these samples were sent to a testing laboratory. The test result showed the ratio of hydrogen to oxygen as 1:8.

a) What conclusion would you draw from the above experiment?

b) Which law of chemical combination does it obey?

The postulates of Dalton’s law are given below:

a) Atom can neither be created nor destroyed.

b) Atoms of different elements may combine with each other in a fixed simple whole number ratio to form compound atoms.

i. Which postulate of Dalton’s atomic theory is based on the Law of Definite Proportions?

ii. Which postulate of Dalton’s Atomic Theory is based on the Law of Conservation of Mass?