Write the chemical name and chemical formula of the salt used to remove permanent hardness of water.

List any two observations when Ferrous Sulphate is heated in a dry test tube?

OR

Identify the products formed when 1 mL of dil. Hydrochloric acid is added to 1g of Sodium metal?

Which of the following is not observed in a homologous series? Give reason for your choice.

a) Change in chemical properties

b) Difference in -CH₂ and 14u molecular mass

c) Gradation in physical properties

d) Same functional group

Why does the Sun appear white at noon?

Both a spherical mirror and a thin spherical lens have a focal length of (-)15 cm. What type of mirror and lens are these?