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Today, after recieveing several messages on our Facebook Fanpage We decided to post today, Chemistry Questions and answers for Nabteb 2012 examinations.
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1ai) Give the name of 3 group II element.
1aii.) Write the electronic configurations of any two of the element named in a(i) above.
i.Electronic Configuration of Magnesium is
2s^2 2p^6 3s^2
ii.Electronic Configuration of Barium is 1s^2 2s^2
2p^6 3s^2 3p^6 4s^2 4p^6 5s^2 5p^6 6s^3
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1aiii.) State three important requirements for polymerization to take place.
1bi.) Give three chemical properties of an acid.
1.) Acids reacts with some metals like iron,
to liberate hydrogen gas.
2HCl(aq) + Zn(s) ->ZnCl2(aq) + H2(g)
2.) Acids reacts with insoluble bases to form salt & water as the only product.
H2SO4(aq) + 2KOH(aq) –>K2SO4(aq)+ 2H20(l)
3.) Acids reacts with trioxocarbonates(IV) to liberate carbon(IV)oxide.
2HCl(aq) + Na2Co3(aq) –>2NaCl(aq) +H2O(l) + Co2(g)
1bii.) Name three methods of preparing salts.
Salt can be prepared using the following methods listed below:.
1.) By titrating an alkali agains an appropriate acid.
2.) By the direct displacement of the hydrogen ion in an acid by a metal more reactive dan hydrogen.
3.) By heating a diluted acid and the base is added a little at a time,until no more base can dissolve.
The excess base is then filtered off, leaving the salt formed in the solution.
1biii.) Give d laboratory test for carbon(IV)oxide.
Bubble the unkown gas through lime water (calcium hydroxide).
If the gas is carbon(IV) oxide, the lime water will turn milky due to the precipitation of insoluble calcium trioxocarbonate(IV).
1ci.) Give the name of a suitable indicator for titration b/w hydrochloric acid and sodium trioxocarbonate.
the name of the suitable indicator for the above titration is Methyl orange because the color at end point is orange and HCl is a strong acid while Na2CO3 is a strong base.
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