Define the terms:
(i) Metals (ii) Non-metals (iii) Metalloids.

Classify the following as pure substances or mixtures: air, milk, graphite, diamond, gasoline, tap water, distilled water, oxygen, one rupee coin, 22 carat gold, steel, iron, sodium chloride, iodized table salt.

Separate the following substances into elements and compounds: Graphite, Diamond, Distilled water, Oxygen, Iron, Sodium chloride, Blue vitriol.

How will you separate the following mixtures?
(i) Oil and water
(ii) Iron-filings and saw dust.
(iii) Glass powder and sugar.

115.

Define the law of conservation of mass. How will you verify this law?

If 6.3g of NaHCO₃ are added to 15.0 g of CH₃COOH solution, the residue is found to weigh 18.0g. What is the mass of CO₂ released in the reaction?

State the law of constant composition or Definite proportion. Explain with suitable examples.

In an experiment 4.68 g iron oxide on reduction with hydrogen yields 3.86 g of iron. In another experiment 3.88 g of iron oxide gives 3.2 g of iron on reduction with hydrogen. Prove that the above data illustrates the law of constant proportions.

Weight of copper oxide obtained by treating 2.16 g of metallic copper with nitric acid and subsequent ignition was 2·7g. In another experiment, 1 · 15 g of copper oxide on reduction yielded 0·92g of copper. Show that the result illustrates the law of definite proportion.