The remains (or impressions) of dead animals or plants, that lived in the remote past, are known as fossils.
(a) Fossils provide evidence for evolution, e.g.r a fossil called Archaeopteryx had feathered wings like birds but teeth and tail like reptiles hence suggesting that birds and reptiles had a common ancestor.
(b) Fossils provide direct evidence of past life and thus provide convincing proof of organic evolution.

(a) The atomic number of element is 17.
(b) It belongs chemically to F(9) because the electronic configuration of F is 2,7 and having same valence electrons.

Mineral :
            It is a naturally occurring substance which contains elements or compounds.
Ores :
       Those minerals which contain a very large percentage of a particular metal and the metal can be extracted economically are called ores.

(a) Metals are malleable and ductile i.e. it can be drawn into sheets and wires, it does not break due to high tensile strength and therefore it can be used for our needs.
(b) Nitric acid is strong oxidising agent, when metals react with nitric acid it does not release H₂ gas as oxidise it to form H₂ O.

(i) Metals are regarded as electropositive elements because they lose electrons to form metal cations.
(ii) When a piece of copper metal is added to .a solution of zinc sulphate, no change takes place since copper is less reactive than zinc and hence will not displace it from zinc sulphate solution. When some zinc is put into blue copper sulphate solution, the blue colour of the copper sulphate solution fades gradually due to the formation of colourless zinc sulphate and red-brown copper metal is deposited on the zinc strip. The reaction takes place as zinc is more reactive than copper.
\(\underset { Copersulphate\\ \quad (Blue) }{ { CuSO }_{ 4 }(aq) } +\underset { Zinc }{ Zn } \rightarrow \underset { ZincSulphate\\ (Colourless) }{ { ZnSO }_{ 4 }(aq) } +\underset { Copper\\ (Red-brown) }{ Cu(s) } \)
(iii) Articles made of aluminium do not corrode even though aluminium is an active metal as a protective layer of aluminium oxide is formed over the aluminium metal.

The method of froth floatation is applied to remove gangue from sulphide ores. In this process, mineral and gangue particles are separated by first wetting the mineral particles with oil and gangue particles with water, and then the mineral particles are carried out by forming froth. Sometimes, depressants are used for separating two sulphide ores by selectively preventing one ore from forming froth. For example, NaCN is used as a depressant for separating two sulphide ores, ZnS and PbS.

(i) When the bar magnet is pushed into the coil, the galvanometer needle would show deflection.
(ii) Withdrawn from the coil, the galvanometer needle would show deflection.
(iii) When the bar magnet is kept stationary inside the coil, when the bar magnet galvanometer needle would show no deflection.

(i) True
(ii) False, the wire with green insulation is the earth wire not the live wire.

Tropic movements are directional movements which are either towards the stimuli or away from it.
(i) Phototropism: Movement is in response to light: stem positive, root negative.
(ii) Geotropism: Movement is in response to gravity: stem negative, root positive.
(iii) Hydrotropism: Movement in response to water: stem negative, root positive.
(iv) Chemotropism: Growth of pollen tubes towards ovules.
For example, the shoot usually grows in the direction of sunlight. This is called positive phototropic movement.

pH in increasing order of H⁺ion concentration is C < E < D < A < B