Sample Chemistry Multiple Choice Paper (A Level standard)
One property of a buffer solution, prepared from a weak acid and its sodium salt, is that
its pH is less than the pH of the original acid. its pH is unafected by the addition of any quantity of H+ ions. its pH is unaffected by the addition of any quantity of OH- ions. its pH is greater than the pH of the original acid. it has a pH of 7.
When a small amount of iodine is shaken with trichloromethane, and water containing dissolved potassium iodide, a purple trichloromethane and a brown aqueous layer are obtained. Suppose more solid potassium iodide were dissolved in the water and the system again allowed to come to equilibrium. What change or changes, if any, would you expect to see in the colours of the two layers?
The brown colour of the aqueous layer becomes paler, but the purple colour of the trichloromethane layer does not change. The brown colour of the aqueous layer becomes more intense, byt the purple colour of the trichloromethane layer becomes paler. The brown colour of the aqueous layer becomes paler in colour, but the purple colour of the trichloromethane layer does not change. Neither the purple colour of the trichloromethane layer, nor the brown colour of the aqueous layer changes in any way. Both the layers become paler in colour.
Which diagram could represent the variation in the concentrations of chemicals M and N with time in the reversible reaction M š N which comes to equilibrium after 400 seconds?
The first seven ionization energies of an element are 1010, 1900, 2900, 5000, 6300, 21 300 and 25 400 kJ/mole respectively. In which group of the Periodic Table is the element?
5 4 3 2 1
The half-life of radioactive Palladium-233 is 28 days. How many days will it take for the radioactivity to fall to one eighth of the initial value?
84 28 112 56 3.5
In which one of the following pairs is the species with the larger radius placed first?
Fe2+, Fe3+ O, S Cl, Cl- IO3+, BrO3+ Li+, F-
Radium has an atomic number of 88. Radium-228 decays by Beta emission with a half-life of 6.7 years. Which of the following statements is correct?
He2+ ions are emitted. The element formed is in the same group of Periodic Table as radium. The radium-228 will have decayed completely in 13.4 years. The relative atomic mass of the element formed is 224. The product of the decay has mass number 228 and atomic number 89.
How many isomers can exist for the octahedral complex ion [Co(NH3)4Cl2]+ ?
6 5 4 3 2
Ethyl ethanoate is hydrolysed by water in the presence of sulphuric acid as a catalyst according to the equation
CH3CO2C2H5 + H2O š C2H5OH + CH3CO2H
The purpose of the sulphuric acid is to
maintain the solution at constant pH. increase the rate of hydrolysis suppress the ionization of the ethanoic acid formed. increase the yield of products. decrease the rate of the reverse reaction.
Which of the following ions CANNOT be formed in aqueous solution by reacting an acid of appropriate concentrations with a metal?
Zn2+ Fe2+ Fe3+ Cu+ Cu2+
The following are standard enthalpies of formation:
CO(g) : -110 kJ/mole
CO2(g) : -394 kJ/mole
H2O(g) : -242 kJ/mole
What is the standard enthalpy change for the following reaction?
An element has an atomic number of 25. Its electronic configuration is
In the diagram, the yellow line represents the energy profile for a homogenous gaseous reaction. Which of the following could produce the red line for the same reaction?
Increase in pressure Increase in volume Increase in concentration of one of the reactants Introduction of a catalyst Increase in temperature
Questions 14 to 19
These questions concern the following elements, which are all members of the same period of the Periodic Table: Sodium, Aluminium, Silicon, Sulphur, Chlorine
Which of these elements has the largest atomic radius?
Sodium Aluminium Silicon Suphur Chlorine
Which of these elements, when combined with hydrogen, forms a complex anion which is widely used as a reducing agent?
Sodium Aluminium Silicon Suphur Chlorine
Which of these elements forms an oxide which is amphoteric?
Sodium Aluminium Silicon Suphur Chlorine
Which of these elements is the strongest reducing agent?
Sodium Aluminium Silicon Suphur Chlorine
Which of these elements disproportionates in cold dilute alkali?
Sodium Aluminium Silicon Suphur Chlorine
Which of these elements forms a high-melting oxide with a giant molecular structure?
Sodium Aluminium Silicon Suphur Chlorine
Questions 20 to 33
Which of the following species has/have a planar structure?
BCl3
NO3-
PH3
I, II and III are correct. I and II are correct. II and III are correct. I is the only correct response. III is the only correct response.
An organic substance reacts with acidified potassium dichromate(VI) solution on warming. Which of the following structures is/are possible for the organic compound?
CH3OH
(CH3)2CHOH
(CH3)3COH
I, II and III are correct. I and II are correct. II and III are correct. I is the only correct response. III is the only correct response.
A real gas fails to obey the ideal gas equation under all conditions because
the molecules do not all have the same velocity.
collisions are not perfectly elastic.
the molecules have a finite size.
I, II and III are correct. I and II are correct. II and III are correct. I is the only correct response. III is the only correct response.
Which of the following solutions does NOT contain solvated chloride ions?
Tetrachloromethane in ethoxyethane.
Hydrogen chloride in methylbenzene.
Chlorine water.
I, II and III are correct. I and II are correct. II and III are correct. I is the only correct response. III is the only correct response.
Which of the following is/are polar?
CH2Cl2
CHCl3
CCl4
I, II and III are correct. I and II are correct. II and III are correct. I is the only correct response. III is the only correct response.
An organic compound contains two atoms of chlorine in each molecule, one of which is much more readily removed than the other when treated with aqueous sodium hydroxide. The compound could be
CH2Cl.COCl
I, II and III are correct. I and II are correct. II and III are correct. I is the only correct response. III is the only correct response.
From the following data:
Zn2+(aq) | Zn, EÆ = -0.76 V
Fe3+(aq), Fe2+(aq) | Pt, EÆ = +0.77 V
it can be deduced that
the standard E.M.F. for the cell Zn|Zn2+(aq) ¦ Fe3+(aq), Fe2+(aq)|Pt is 0.01 V.
zinc is a more powerful reductant than Fe2+ ions.
Fe3+ can oxidize zinc under standard conditions.
I, II and III are correct. I and II are correct. II and III are correct. I is the only correct response. III is the only correct response.
Francium has the highest relative atomic mass of the Group I elements. It may be predicted that
only oxygen would be given off as a gas when francium nitrate is heated.
the bonding in francium chloride would show predominantly covalent character.
francium sulphate would be precipitated from solution if dilute sulphuric acid added to a solution of francium nitrate.
I, II and III are correct. I and II are correct. II and III are correct. I is the only correct response. III is the only correct response.
Vanadium (electronic configuration Ar 3d34s2) exists in the oxidation state(s).
0
+2
+4
I, II and III are correct. I and II are correct. II and III are correct. I is the only correct response. III is the only correct response.
For which of the following is ΔHÆ positive?
O+(g) + e- ® O(g)
O(g) + e- ® O-(g)
O-(g) + e- ® O2-(g)
I, II and III are correct. I and II are correct. II and III are correct. I is the only correct response. III is the only correct response.
Which of the following properties of the Group 1 elements increase(s) with increasing atomic number?
First ionization energy
Melting point
Atomic radius
I, II and III are correct. I and II are correct. II and III are correct. I is the only correct response. III is the only correct response.
On oxidation, a compound C4H10O can be converted into a compound C4H8O. The original compound could be a
primary alcohol
secondary alcohol
tertiary alcohol
I, II and III are correct. I and II are correct. II and III are correct. I is the only correct response. III is the only correct response.
The amount of carbon dioxide present at equilibrium in the reaction
CaCO3(s) š CaO(s) + CO2(g)
ΔHÆ298 = +178 kJ/mole
can be INCREASED by
raising the temperature
raising the pressure
adding some more solid calcium oxide
I, II and III are correct. I and II are correct. II and III are correct. I is the only correct response. III is the only correct response.
The element with atomic number 18 has a relative atomic mass of 40 and electronic structure 1s22s22p63s23p6. It follows that the element with atomic number 19
forms ions of electronic structure 1s22s22p63s23p6
has electronic structure is 1s22s22p63s23p64s1
has a relative atomic mass of 41
I, II and III are correct. I and II are correct. II and III are correct. I is the only correct response. III is the only correct response.
Questions 34 to 37
These questions concern the determination of the relative molecular mass of a liquid using the apparatus shown below
A small quantity of air was drawn into the gas syringe and the rubber cap put over the nozzle. Steam was passed through the jacket. When the thermometer reading and volume of air reached steady values these were recorded.
A small hypodermic syringe containing the liquid was weighed. The liquid was injected through the rubber cap and the syringe reweighed immediately.
When the volume of air plus vapour again reached a steady value it was recorded. The following results were obtained:
Temperature of the steam jacket = 99oC.
Volume of air in the gas syringe = 7cm3.
Initial mass of the hypodermic syringe plus liquid = 8.36g
Final mass of the hypodermic syringe = 8.21g
Volume of vapour plus air = 84 cm3
Atmospheric pressure = 753 mmHg.
If the value of the gas constant R = 0.082 atm litres /oC / mole, the relative molecular mass of the liquid is given by
0.15 x 0.082 x 0.084372 x 753
0.15 x 99 x 7530.077 x 0.082 x 760
0.082 x 372 x 7600.15 x 77 x 753
0.15 x 0.082 x 372 x 7600.077 x 753
0.082 x 0.77 x 7530.15 x 99
Which of the following experimental errors would cause the value of the relative molecular mass, calculated fromt he experimental results, to be LOWER than the correct value?
Injection of a bubble of air, in addition to the liquid, into the gas syringe. Injection oc the liquid so that some of it remained int he neck of the gas syringe. Leakage of the vapour from the gas syringe through the rubber cap. Evaporation of some of the liquid from the hypodermic syringe between the two weighings. Measuring the volume of vapour and air before it had reached the temperature of the steam jacket.
Which of the following modifications to the experimental procedure would improve the accuracy of the value of the relative molecular mass calculated from the results?
Finding the mass of liquid used by weighing the gas syringe and again when the liquid has been added, instead of weighing the hypodermic syringe. Repeating the experimental using different masses of the liquid, measuring the volume of vapour produced each time and then using these results graphically to determine the density of the vapour. Omitting the air from the gas syringe. Using a smaller mass of the liquid. Heating the gas syringe with an electric light bulb instead of using steam.
A similar experiment at 130oC using ethanoic acid, CH3CO2H, as the liquid gave a value for its relative molecular mass of 120 instead of the expected value of 60.
An explanation for this result could be that under the conditions of the experiment
the volume of the ethanoic acid molecules is NOT negligible in comparison with the total volume of the vapour. ethanoic acid vapour exists in the form of the dimer (CH3CO2H)2. the molecule of ethanoic acid partially dissociates CH3CO2H(g) š H+(g) + CH3CO2-(g) ethanoic acid decomposes to methane and carbon dioxide: CH3CO2H(g) ® CH4(g) + CO2(g) vapours of volatile liquids deviate from ideal gas behaviour
Questions 38 to 40
These questions concern rates of hydrolysis of some halogenalkanes. Three halogenalkanes were tested in the following manner: 1 cm3 of ethanol was placed in a test tube and 3 drops of the halogenalkane were added. The test tube was placed in a water bath and heated to 60oC. 2 cm3 of 0.l Molar silver nitrate was then added.
Why was the ethanol added?
It indicates when the silver halide has been precipitated. It prevents the immediate precipitation of the silver halide. It acts as an electrophile. It catalyses the reaction. It acts as a solvent for the halogenoalkane.
The experiment was carried out on four halogenoalkanes, and the appearance of the liquid three minutes after the start of the heating was noted. Here are the results:
1-chloro-butane: Clear
1-bromo-butane: Cloudy
1-iodo-butane: Heavy precipitate
Which of the following best explains these results?
The solubility products of the silver halides decreases as you go down the halogens from chlorine to iodine. The strength of a carbon-chlorine bond is stronger than that of a carbon-bromine bond, which is in turn greater than a carbon-iodine bond. The three reactions occur through three totally different mechanisms. The electronegativities of the halogens decrease as you go down the group from chlorine to iodine. The halogens increase in size as you go down the group.
Which of the following, which are all isometric chloropentanes, would produce a precipitate most quickly in a similar experiment?
its pH is less than the pH of the original acid.
its pH is unafected by the addition of any quantity of H+ ions.
its pH is unaffected by the addition of any quantity of OH- ions.
its pH is greater than the pH of the original acid.
it has a pH of 7.
