Available Answers

1. 1.

   State reasons for the following statements.

   1. Burning of paper is a chemical change.
   2. The rate of evaporation increases with increase in surface area.
   3. Sublimation is a physical change.
2. 2.

   Match the columns.

   Compound	Constituents	Formula
   Water	Sodium, carbon, oxygen	NaHCO3
   Washing soda	Carbon, hydrogen, oxygen	NaCl
   Baking soda	Oxygen, hydrogen	CH3COOH
   Common salt	Silicon, oxygen	H2O
   Vinegar	Sodium, chlorine	SiO2
   Sand	Sodium, hydrogen, carbon, oxygen	Na2CO3

    

3. 3.

   Anubhav wants to separate a mixture of common salt and ammonium chloride. Which method should he adopt to separate the mixture? Discuss the method in detail.

4. 4.

   The teacher asks Humaira to separate a mixture of iron filings, sand and iodine. How can she do that?

5. 5.

   Avantika wants to know the difference between an anion, a cation and a radical. Help her understand the same with the help of a few examples of anions and cations along with their representation.

6. 6.

   On the basis of your understanding of periodic table, answer the following questions.

   1. What are the columns and rows in a periodic table called? How many rows and columns are there?
   2. On what basis are the columns in a periodic table arranged?
   3. How is the process carried out?
   4. In which groups and periods do the following elements exist: sodium, calcium, barium, silver and germanium?