NABTEB CHEMISTRY OBJECTIVE
(1ai)Give the name of 3 group II element.
Answer:- 1) Magnesium(Mg) 2) Barium(Ba) 3) Calcium(Ca)
(1aii)Write the electronic configurations of any two of the element named in a(i) above.
Answer:- i.Electronic Configuration of Magnesium is 1s^2 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
NOTE:- Pls note dat dis sign ^ means raise to power.
(1aiii)State 3 important requirements for polymerization to take place.
(1bi)Give 3 chemical properties of an acid.
Answer:- 1)Acids reacts with some metals like iron,zinc,magnesium to liberate hydrogen gas.
Equation:- 2HCl(aq) + Zn(s) ->ZnCl2(aq) + H2(g)
2)Acids reacts with insoluble bases to form salt&water as d only product.
Equation:- H2SO4(aq) + 2KOH(aq) –>K2SO4(aq) + 2H20(l)
3)Acids reacts with trioxocarbonates(IV) to liberate carbon(IV)oxide.
Equation:- 2HCl(aq) + Na2Co3(aq) –>2NaCl(aq) + H2O(l) + Co2(g)
(1bii)Name 3 methods of preparing salts.
Answer:- Salt can be prepared using d following methods:-
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 e.g zinc
3)By heating a diluted acid&the base is added a little at a time,until no more base can dissolve.
the excess base is den filtered off,leaving d salt formed in d solution.
(1biii)Give d laboratory test for carbon(IV)oxide.
Answer:- 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 d name of a suitable indicator for titration b/w hydrochloric acid and sodium trioxocarbonate (IV) solution.
Answer:- the name of the suitable indicator for the above titration is Methyl orange becos the color at end point is orange and HCl is a strong acid while Na2CO3 is a strong base.
This is more Nabteb chemistry questions,pls study it and answer, Good luck!
(H=1.00, C=12.00, O=16.00, Na=23.00, Cl=35.00, molar volume of all gases =22.4dm^3 at s.t.p).
2(a)i, give two physical properties of each of the following: diamond, graphite, coal.
(ii) name four products of the destructive distillation of coal.
(iii) describe the laboratory preparation of carbon(iv)oxide with the aid of a well lebelled diagram.
(2b) briefly describe each of the following:
(i) amphoteric oxide.
(ii) acid salt
3.(a) i. Briefly discribe TWO crystaline allotropes of sulphur.
(ii) write a balanced equation of what happens when a piece of sulphur is burnt in air.
(iii) write a balanced equation to describe the reaction of the product in
(aii) above with: pure water, dilute sodium hydroxide solution.
(Bi) describe the laboratory preparation of hydrogen sulphide. (no diagram required).
(ii) give a chemical test for H2S(hydrogen sulphide).
(C) with the aid of a balanced equation describe THREE chemical properties of dilute H2SO4.
4. (ai) what is craking? Write a balanced equation to illustrate craking.
(ii) name FOUR fractions of petroleum and mention ONE use of each of them.
(bi) briefly describe the extraction of calcium metal.
(ii) state THREE chemical properties of calcium hydroxide.
(c) calculate the percentage purity of a sample of limestone when 25.0g of it produce 12.6g of CaO when strongly heated in a kiln.
5. (a) little quantities of the following were mixedwith pure water in a beaker.
Sodium chloride,potassium trioxocarbonate(IV) and calcium tetraoxosulphate(IV).
(i) name THREE anions present in the solution.
(ii) name THREE cations present in the solution.
(bi) briefly explain the following terms.
Saturated vapour pressure,(SVP).
Standard temperature and pressure,(STP)
(ii ) an element Qy occurs naturally having THREE isotopes whose percentage compositionsare as follows:
37 Qy=40% 17 38 Qy=25% 17 39 Qy=35% 17
: calculate the relative atomic mass of Qy.
(c) use kinetic theory to explain this phenomenon:
A distillation flask containing ethanol solution fixed with a thermometer was heatedat 78^oC, ethanol was boiling off but the temperature remained constant untill all the ethanol distilled off.
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