A mixture of iron and sulphur can be separated by dissolving the mixture in?
отговор
(D)
benzene
3
A given amount of gas occupies 10.0 dm3 at 4atm and 273°C. The number of moles of the gas present is?
(Molar volume of a gas at s.t.p. = 22.4 dm3)
отговор
(A)
0.89 mol
4
8.0 g of an element X react with an excess of copper (ll) tetraoxosulphate (lV) solution to deposit 21.3 g of copper. The correct equation for the reaction is?
(Cu = 64).
отговор
(A)
X(s) + CuSO4(aq) → Cu(s) + XSO4(aq)
5
C3H8(g) + 502(g) → 4H2O + 3CO2(g). Form the equation above the volume of oxygen at s.t.p. required to burn 50cm3 of propane is?
отговор
(A)
250 cm3
6
30cm3 of hydrogen was collected over water at 27°C and 780 mm Hg. If the vapour pressure of water at the temperature of the experiment was 10 mm Hg, calculate the volume of the gas at 760 mm Hg and 7°C?
отговор
(C)
28.4 cm3
7
If sulphur (IV) oxide and methane are released simultaneously at the opposite ends of a narrow tube, the rates of diffusion Rso2 and Rch4 will be in the ratio?
(S = 32, O = 16, C = 12, H = 1)
отговор
(C)
1:2
8
A solid begins to melt when?
отговор
(D)
energy of vibration of particles of the solid equals the intermolecular forces
9
Which of the following electron configurations indicates an atom with the highest ionization energy?
отговор
(A)
2,8,7
10
The line observed in the sample hydrogen spectrum are due to emission of?
отговор
(C)
energy by electron transition
11
The property used in obtaining oxygen and nitrogen industrially from air is the?
отговор
(A)
boiling point
12
Potassium tetraoxomanganate (VII) is often added to impure water to?
отговор
(C)
destroy bacteria and algae
13
The soil around a battery manufacturing factory is likely to contain a high concentration of?
отговор
(B)
Pb2+ salts
14
Excess phosphorus was burnt in a gas jar and the residual gas passed successively over concentrated KOH solution and concentration H2SO4 before being collected in a flask. The gases collected are?
отговор
(B)
nitrogen and the rare gases
15
If an element X of an atomic number Z and mass number Y is irradiated by an intense concentration of neutrons, the relevant nuclear equation is?
отговор
(B)
yzX + 10n → y + 1zX
16
90.0g of MgCI2 was placed in 50.0cm3 of water to give a saturated solubility of the salt is 8.0 mol dm3 at the same temperature, what is the mass of the salt left undissolved at the given temperature?
(Mg = 24, Cl = 35.5)
отговор
(A)
52.0g
17
Soap lather is an example of a colloid in which a?
отговор
(C)
gas is dispersed in liquid
18
The pH of a solution obtained by mixing 100cm3 of a 0.2M solution of NaOH is?
отговор
(D)
12.7
19
Mg2+(aq) + 2e->(aq) → Mg(s)E°(volts) = 2.370
Zn2+(aq) + 2e->(aq) → Zn(s)E°(volts) = -0.763
Cds2+(aq) + 2e->(aq) → Cd(s)E°(volts) = 0.403
Cu2+(aq) + 2e->(aq) → Cu(s)E°(volts) = 0.340
In the electrochemical series above, the strongest reducing agents is?
отговор
(D)
Mg(s)
20
2Cl2(g) + 2H2O(g) 4HCl(g) + O2(g)
∆H° = +115KJ mol-1. In the above equilibrium reaction, a decrease in temperature will?
отговор
(A)
favour the reverse reaction
21
2X(g) + Y(g) → Z(g): In the equation above, The rate of formation of Z is found to be independent of the concentration of Y and to quadruple when the concentration of X is doubled. The correct equation for the reaction is?
отговор
(D)
R = K (X) 2(Y)°
22
A gas that turns a filter paper previously soaked in lead ethanoate solution black is?
отговор
(B)
hydrogen sulphide
23
3CuO(s) + 2NH3(g) → 3Cu(s) + 3H2O(I) N2(g) (i).
2NH3(g) + 3Cl2(g) → 6HCl(g) + N2(g) (ii).
4NH3(g) + 3O2(g) → 6H2O(I) + 2N2(g) (iii).
The reactions represented by the equations above demonstrate the?
отговор
(C)
reducing properties of ammonia
24
A solution containing chloride ions gives white precipitate with silver trioxonitrate(V) Solution. The precipitate will be insoluble in dilute?
отговор
(A)
HNO 3 but soluble in ammonia solution
25
The oxide that remains unchanged when heated in hydrogen is?
отговор
(D)
ZnO
26
Which of the following is observed when a solution of iron (III) chloride is mixed with a solution of sodium hydroxide?
отговор
(D)
A brown precipitate is formed
27
The metal that will react with water only in the form of steam to librate hydrogen gas is?
отговор
(C)
iron
28
A common characteristic shared by iron and aluminium is that both?
отговор
(A)
are extracted by reduction methods
29
Alloys are often used in preference to pure metals because?
отговор
(C)
metallic properties are improve in alloys
30
One mole of hydrocarbon contains 6g of hydrogen. If the molecular weight is 54, the hydrocarbon is an?
отговор
(D)
alkyne
31
On cracking medicinal paraffin, a gas is evolved which gives a pop sound with a lighted splinter and an oily liquid which decolourizes bromine solution is also obtained. The products of the cracking are ?
отговор
(C)
hydrogen gas and alkene
32
How many structural isomers can be drawn for the non-cyclic alkanol with molecular formula C 4H10O?
отговор
(D)
4
33
An example of aromatic compound is?
отговор
(C)
C6H5OH
34
Terylene is synthesized from ethane- 1, 2-diol and benzene - 1, 4-dicarboxylic acid by?
отговор
(B)
condensation reaction
35
Which of the following is true concerning the properties of benzene and hexane?
