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Question 1 What suggestion was made by the Indian sage Kanada regarding nature of matter? Ans The Indian sage Kanada suggested that " all matter is composed of very small particles." Question 2 Name one compound which is covalent but on dissolving in water conducts electricity? Ans. Hydrogen Chloride ( HCL) Question 3 What is the chemical formula of Ferric carbonate and washing soda? Ans. ferric carbonate = fe2( c03)3 washing soda + Na2Co3 Question 4 Nucleus does not contain any electrons ( or B-particles) explain how beta particles are emitted in the radioactive change.? Ans. It is believed that B particles (or electrons) are ejected during radioactive change as a result of neutron decay. Neutron -> Proton + electron Question 5 Give one property of Mgcl2 which agrees with it being an ionic compound. Ans. Mgcl2 is readily soluble in water and when Agno3 solution is added to its aqueous solution, a white precipitate. is immediately formed. This shows that Mgcl2 is an ionic compound. Question 6 Why are ionic bonds non- directional? Ans. In ionic bond, the attraction between oppositely charged ions is equally strong in all directions. Hence ionic bonds are non- directional. Question 7 how many moles of oxygen would be librated on heating one mole of potassium chlorate? Ans. ∆ 2KClO3 ----> 2 KCl + 3O2 (two moles) of KClO3 gives on heating = (3 Moles of oxygen) 1 moles ---KClO3 gives on heating give------------------------= 3/2 moles of oxygen = 1.5 moles of oxygen

Question 8 A molten salt solution conducts electricity but solid does not Explain Ans. In molten salt , the salt (Na+cl-) is present in free mobile ions (Na+cl -) which are capable of carrying electricityHence molten state conducts electricity. On the other hand , in solid state , the (Na+cl -) ions are fixed at definite positions in crystal lattice. Hence solid salt does not conduct electricity. Question 9 Why do carbon atoms form polymers with co-valent bonds? Give Examples. Ans. The velency of carbon atoms is four and this unables carbon to make a long chain of covalant bonds with other carbon atoms, thereby resulting in the formation of long thread like molecules of high molecular weight , called polymers. HHHHHHHH eg. polythene or polyethyle . ......c-c-c-c-c-c-c-c...... HHHHHHHH Question 10 what is meant by the dissociation How is it different from ionization? Give Examples. Ans. when a substance breaks up into two or more substance it is called dissociations for eg when pottassium chlorate is heated, oxygen and pottassium chloride are formed ∆ 2 KCLO3(s) ------> 2 KCl(S) + 3O2 ( g) when an electroyte breaks up into positively and negatively charged ions in water it is called ionization . for eg. when sodium chloride is added into water it ionizes into sodium and chloride ions Thus Nacl <----> Na + cl Question 11 A strip of impure silver metal is given to you .Describe briefly the apparatus you would use to refine it electrolytic ally. Write equations of the reactions involved in the process . Make a figure for this Ans. . Electrolytic refining of impure silver is carried out in the cell containing silver nitrate solution as an electrolyte.A strip of impure silver metal is made anode and a strip of pure silver is made cathode . During eletrolysis, following reactions are involved: AgNO3 <------> Ag+ + NO3- ( ionization ) (electrolyte) at cathode : Ag+ + e- -----> AG ( pure silver deposited) at anode : Ag+ - e- -----> Ag+ ( added to electrolyte) thus , impure anode dissolves and pure silver is deposited at the cathode.