35 cm3 of hydrogen was sparked with 12 cm3 of oxygen at 110°C and 760mm Hg to produce steam. What percentage of the total volume of gas left after the reaction is hydrogen?
إجابة
(B)
31%
2
2.85g of an oxide of copper gave 2.52g of copper on reduction and 1.90g of another oxide gave 1.52g of copper on reduction. The data above illustrates the law of?
إجابة
(D)
multiple proportions
3
An element, X, forms a volatile hydride XH3 with a vapour density of 17.0. The relative atomic mass of X is?
(H = 1)
إجابة
(B)
31.0
4
A mixture of 0.20 mole of Ar, 0.20 mole of N2 and 0.30 mole of He exerts a total pressure of 2.1 atm. The partial pressure of He in the mixture is?
إجابة
(A)
0.90 atm
5
The temperature of a body decreases when drops of liquid placed on it evaporate because?
إجابة
(C)
the heat of vapourization is drawn from the body causing it to cool
6
The electron configuration of two elements with similar chemical properties are represented by?
إجابة
(C)
1s22s22p63s1 and 1s22s1
7
In the periodic table, what is the property that decreases along the periodic and increases down the group?
إجابة
(D)
Atomic radius
8
Two elements, P and Q with atomic numbers 11 and 8 respectively , combine chemically to form the compound PxQY. The respective values of x and y are?
إجابة
(C)
2 and 1
9
Oxygen is a mixture of two isotopes 16-O and 18-O with relative abundances of 90% and 10% respectively. The relative atomic mass of oxygen is?
إجابة
(B)
16.2
10
If 30cm\(^3\) of oxygen diffuses through porous plug in 7s, how long will it take 60 cm\(^3\) of chlorine to diffuse through the same plug?
إجابة
(C)
21s
11
200 cm3 of air was passed over heated copper in a syringe several times to produce copper (II) oxide.
When cooled, the final volume of air recorded was 158cm3. Estimate the percentage of oxygen in the air?
إجابة
(C)
21%
12
On recrystallization, 20g of magnesium tetraoxosuphate (IV) forms 41 g of magnesium tetraoxosulphate (IV) crystals, MgSO4. yH2O. The value of y is?
(Mg = 24, S = 32, O = 16, H = 1)
إجابة
(D)
7
13
Which of the following gases is the most dangerous pollutant?
إجابة
(D)
Carbon (ll) oxide
14
A major process involved in the softening of hard water is the?
إجابة
(A)
conversion of a soluble calcium salt to its trioxoncarbonate (lV)
15
A saturated solution of AgCl was found to have a concentration of 1.30 x 10-5 mol dm-3. The solubility product of AgCl therefore is?
إجابة
(C)
1.69 x 10-10 mol2 dm-6
16
The hydroxyl ion concentrated, (OH-), in a solution of sodium hydroxide of pH 10.0 is?
إجابة
(C)
10-4 mol dm-3
17
Which of the aqueous solutions with the pH values below will liberate hydrogen when it react with magnesium metals?
إجابة
(D)
3.0
18
Given that 15.00 cm3 of H2
SO4 was required to completely neutralize 25.00 cm3 of 0.125 mol dm-3 NaOH, calculate the molar concentration of the acid solution:
إجابة
(C)
0.104 mol dm-3
19
When platinum electrodes are used during the electrolysis of copper (ll) tetraoxosulphate (lV) solution, the solution gets progressively?
إجابة
(A)
acidic
20
How many Faraday of electricity are required to deposit 0.20 mole of nickel, if 0.10 Faraday of electricity deposited 2.98g of nickel during electrolysis of its aqueous solution?
(Ni = 58.7, 1F = 96 500 C mol-)
إجابة
(C)
0.40
21
What is the oxidation number of Z in K3ZCl6?
إجابة
(B)
+3
22
2H2S(g) + SO2(g) + H2O(I) → 3S(s) + 3H2O(I)..........(i) 3CuO(s) + 2NH3(g) → 3Cu(s) + 3H2O(I) + N2(g).........(II) In the equations above, the oxidizing agent (I) and the reducing agent in (II) respectively are?
إجابة
(C)
SO2 and NH3
23
2SO2(g) + O2(g) → 2SO3. In the reaction above, the standard heats of formation of SO2(g) and SO3(g) are -297 KJ mol-1 and -396 kJ/mol respectively. The heat change of the reaction is?
إجابة
(B)
-198 kJ mol-
24
If the rate law obtained for a given reaction is rate = k(X)n (Y)m, what is the overall order of the reaction?
إجابة
(C)
n + m
25
One method of driving the position of equilibrium of an endothermic reaction forward is to?
إجابة
(A)
increase temperature at constant pressure
26
Oxidation of concentrated hydrochloric acid with manganese (IV) oxide liberates a gas used in the?
إجابة
(D)
sterilization of water
27
mE + nF → pG + qH. In the equation above, the equilibrium constant is given by?
إجابة
(C)
(G)p(H)q / (E)m(F)n
28
A compound that will NOT produce oxygen on heating is?
إجابة
(A)
potasium dioxonitrate (III)
29
Coal gas is made up of carbon (II) oxide, hydrogen and?
إجابة
(D)
methane
30
2X(aq) + MnO2(s) + 4H+(aq) → X2(g) + Mn2+(aq) + 2H2O.
The reaction above can be used for the laboratory preparation of all halogens except fluorine because it is?
إجابة
(D)
highly reactive
31
The removal of rust from iron by treatment with tetraoxosulphate (IV) acid is based on the?
إجابة
(C)
oxidationof the rust
32
Which of the additives could improve the quality of steel?
إجابة
(D)
Chromium and nickel
33
Sodium hydroxide is prepared commercially from sodium chloride solution by?
إجابة
(A)
electrolysis using mercury as cathode
34
A sample of a substance containing only C and H burns in excess O2 to yield 4.4g of CO2
and 2.7 g of H2O. The empirical formula of a substance is?
(C = 12, O = 16, H = 1)
إجابة
(A)
CH3
35
An undesirable paraffin in the petroleum industry which is particularly prone to knocking is?
إجابة
(B)
n-heptane
36
The reaction of an alkanol with an alkanoic acid in the presence of concentrated H2SO4 will produce an?
إجابة
(B)
alkanoate
37
The final product of the reaction of ethyne with hydrogen iodide is?
إجابة
(A)
CH3—CHI2
38
Synthetic rubber obtained by the polymerization of chlorobutadiene in the presence of sodium is called?
إجابة
(D)
neoprene
39
The synthetic detergents are preferred to soap for laundry using hard water because?
إجابة
(B)
the calcium salts of detergents are water soluble
40
25 cm\(^3\) of 0.02 M KOH neutralized 0.03 g of a monobasic organic acid having the general formula C\(_n\)H\(_{2n + 1}\)COOH. The molecular formula of the acid is?
(C = 12, H = 1, O = 16)
إجابة
(C)
CH3COOH
41
\(\frac{1}{2}\)N\(_2\)(g) + \(\frac{1}{2}\)O\(_2\)(g) → NO(g) ∆H° = 89 KJ mol\(^{-1}\). If the entropy change for the reaction above at 25°C is 11.8 J mol\(^{-1}\), calculate the change in free energy. ∆G°, for the reaction at 25°C?
إجابة
(B)
85.48 KJ
42
Use the graph above to answer this question. A sample, X, solid at room temperature, was melted, heated to a temperature of 358 K and allowed to cool as shown in OPQR. The section PQ indicates that X is
إجابة
(D)
a pure compound
43
Use the graph above to answer this question. A sample, X, solid at room temperature, was melted, heated to a temperature of 358 K and allowed to cool as shown in OPQR.The section OP suggests that X is in the
إجابة
(A)
liquid sate
44
In the diagram above the gas Y could be
إجابة
(A)
hydrogen chloride
45
The IUPAC nomenclature of the organic compound with the above structural formula is
