In order to verify the law of conservation of mass, we carry out chemical reactions in a closed container, so that

Mr. Seema taught mole concept to the students of class IX and asked the students to revise whatever had been taught. In the next period, she divided the class into several groups and asked each member of each group to explain what they have understood to the other members of their group.

Afreen a member of one of the group started to explain mole concept to the other members of her group as follow. Number of moles of molecules is equal to its mass and it is also equal to the Avogadro’s number.

Read the above passage and answer the following questions.

(i) Comment on Afreen’s understanding of mole concepts. What modification do her statement need?

(ii) What is the unit of Avogadro’s number?

(iii) What are the value displayed by Mrs. Seema?

Antacid are prescribed during acidity. Commercially available antacids consist of magnesium hydroxide [Mg(OH)₂], sugar and flavouring agents. The magnesium hydroxide act as base and form salt and water on reaction with hydrochloric acid of the stomach. The mass of salt and water formed is equal to the combined mass of

Which of the following represents a correct chemical formula? Name it.

Four students A, B, C and D verified the law of conservation of mass by performing chemical reaction between barium chloride and sodium sulphate. All of them took 107.2 g barium chloride solution and 116.1g of sodium sulphate solution and mixed them in the beaker of mass 150 g. They reported their results as follows:

The correct observation is that of student.