The concentration of a salt solution in terms of mass by mass percentage is $20 \%$ and the mass of the solution is $550 \text{ g}$. Determine the mass of solute present in the solution. (in $\text{ g}$)

Define a solution. Give an example of $(i)$ gas in liquid solution $(ii)$ gas in gas solution.

Classify the following as physical or chemical properties:
$(a)$ The composition of a sample of steel is: $98\%$ iron,$1.5\%$ carbon,and $0.5\%$ other elements.
$(b)$ Zinc dissolves in hydrochloric acid with the evolution of hydrogen gas.
$(c)$ Metallic sodium is soft enough to be cut with a knife.
$(d)$ Most metal oxides form alkalis on interacting with water.

Tincture of iodine has antiseptic properties. This solution is made by dissolving

Calculate the mass of sodium sulphate required to prepare its $20\%$ (mass percent) solution in $100\,g$ of water. (in $,g$)

Classify the substances given in the figure into elements and compounds.