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Class 9Class 10First YearSecond Year
$(d) Calculate the oxidation numbers of the elements underlined in the following compounds.(ii) \mathrm{Na}_{2} \mathrm{CO}_{3}$

$9. \mathrm{lg} equivalent weight of \mathrm{Al} is equal to(a) 9 \mathrm{~g} (b) 27 \mathrm{~g} (c) 54 \mathrm{~g} (d) \mathrm{lg}$

$(b) Balance the following equations by oxidation number method(iii) \mathrm{Br}_{2}+\mathrm{NaOH} \rightarrow \mathrm{NaBr}+\mathrm{NaBrO}_{3}+\mathrm{H}_{2} \mathrm{O}$

$(b) Balance the following ionic equations by ion-electron method.(iv) \mathrm{Cu}+\mathrm{NO}_{3}^{1-} \rightarrow \mathrm{Cu}^{2+}+2 \mathrm{NO}_{2}$

$Q.1 Multiple choice questions.(v) If a strip of Cu metal is placed in a solution of \mathrm{FeSO}_{4} :(a) Cu will be deposited(b) Fe is precipitated out(c) Cu and Fe both dissolve(d) No reaction take place$

$21. In electroplating of silver from where \mathrm{Ag}^{+} ions come and where they deposit?$

$(b) Balance the following equations by oxidation number method(ix) \mathrm{NaCl}+\mathrm{H}_{2} \mathrm{SO}_{4}+\mathrm{MnO}_{2} \rightarrow \mathrm{Na}_{2} \mathrm{SO}_{4}+\mathrm{MnSO}_{4}+\mathrm{H}_{2} \mathrm{O}+\mathrm{Cl}_{2}$