Available Answers

1. 1.

   Differentiate between the terms elements, compounds & mixtures with suitable examples.

2. 2.

   State which element exists in the highest percentage in - a) earth's crust b) atmosphere c) human body.

3. 3.

   Elements are mainly classified into metals & non-metals. State six properties of metals which differ from non-metals.

4. 4.

   Give the symbols of the following elements - & state in each case whether they are metals, non-metals, metalloids or noble gases.

   a) potassium b) carbon c) oxygen d) mercury e) flourine f) neon g) sulphur h) zinc i) boron j) copper k) calcium l) xenon m) arsenic n) mercury o) chlorine p) silicon q) neon r) lead s) antimony t) sodium u) iodine v) platinum w) radon x) phosphorus y) bromine z) aluminium

5. 5.

   State what is meant by the term 'activity series of metals'. State the most reactive & the least reactive metal from the following - Zn, Ag, Na, Fe, Cu, Pb.

6. 6.

   Give three reasons why - carbon dioxide is considered a compound, while carbon - an element.