Y12 PRACTICE TEST – JAN 11
1. (i) Calcium carbonate is added to separate solutions of hydrochloric acid and ethanoic acid of the same concentration. State one similarity and one difference in the observations you could make.
ANSWER
(2)
(ii) Write an equation for the reaction between hydrochloric acid and calcium carbonate.
ANSWER
(2)
(iii) Determine the volume of 1.50 mol dm–3 hydrochloric acid that would react with exactly 1.25 g of calcium carbonate.
ANSWER
(3)
(iv) Calculate the volume
of carbon dioxide, measured at 273 K and
1.01×105 Pa, which would be produced when 1.25 g of calcium carbonate reacts
completely with the hydrochloric acid.
ANSWER
(2)
(Total 9 marks)
2. Calcium carbonate decomposes on heating as shown below.
CaCO3 → CaO + CO2
When 50 g of calcium carbonate are decomposed, 7 g of calcium oxide are formed. What is the percentage yield of calcium oxide?
A. 7%
B. 25%
C. 50%
D. 75%
ANSWER
(Total 1 mark)
3. What is the purpose of the beam of high energy electrons used in a mass spectrometer?
A. To ionize atoms
B. To accelerate ions
C. To deflect ions
D. To detect ions
ANSWER
(Total 1 mark)
4. The relative molecular mass (Mr) of a compound is 60. Which formulas are possible for this compound?
I. CH3CH2CH2NH2
II. CH3CH2CH2OH
III. CH3CH(OH)CH3
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
ANSWER
(Total 1 mark)
5. The
element vanadium has two isotopes, 
and 
and a relative atomic mass of 50.94.
(a) Define the term isotope.
ANSWER
(1)
(b) State the number of
protons, electrons and neutrons in 
ANSWER
(2)
(c) State and explain which is the more abundant isotope.
ANSWER
(1)
(d) State the name and the mass number of the isotope relative to which all atomic masses are measured.
ANSWER
(1)
(Total 5 marks)
6. The diagram below (not to scale) represents some of the electron energy levels in the hydrogen atom.
________________________________ n = ¥
________________________________ n = 6
________________________________ n = 5
________________________________ n = 4
________________________________ n = 3
________________________________ n = 2
________________________________ n = l
(i) Draw an arrow on the diagram to represent the electron transition for the ionization of hydrogen. Label this arrow A.
ANSWER
(2)
(ii) Draw an arrow on the diagram to represent the lowest energy transition in the visible emission spectrum. Label this arrow B.
ANSWER
(2)
(Total 4 marks)
7. The element bromine exists as the isotopes 79Br and 81Br, and has a relative atomic mass of 79.90.
(a) Complete the following table to show the numbers of sub-atomic particles in the species shown.
|
an atom of 79Br |
an ion of 81Br– |
|
protons |
|
|
|
neutrons |
|
|
|
electrons |
|
|
ANSWER
(3)
(b) State and explain which of the two isotopes 79Br and 81Br is more common in the element bromine.
ANSWER
(1)
(c) The element calcium is in the same period of the Periodic Table as bromine.
(i) Write the electron arrangement for an atom of calcium.
ANSWER
(1)
(ii) Deduce the formula of the compound calcium bromide.
ANSWER
(1)
(Total 6 marks)
8. (a) Describe the following stages in the operation of the mass spectrometer.
(i) ionization
ANSWER
(2)
(ii) deflection
ANSWER
(2)
(iii) acceleration
ANSWER
(1)
(b) (i) State the meaning of the term isotopes of an element.
ANSWER
(1)
(ii) Calculate the percentage abundance of the two isotopes of rubidium 85Rb and 87Rb.
ANSWER
(2)
(iii) State two physical properties that would differ for each of the rubidium isotopes.
ANSWER
(1)
(iv) Determine the full electron configuration of an atom of Si, an Fe3+ ion and a P3– ion.
ANSWER
(3)
(Total 12 marks)
9. (i) Explain why successive ionization energies of an element increase.
ANSWER
(1)
(ii) Explain how successive ionization energies account for the existence of three main energy levels in the sodium atom.
ANSWER
(3)
(Total 4 marks)
10. What is the electron configuration for the copper(I) ion, (Z = 29)?
A. [Ar]4s23d9
B. [Ar]4s13d10
C. [Ar]4s13d9
D. [Ar]3d10
ANSWER
(Total 1 mark)
11. How many lone pairs and bonding pairs of electrons surround xenon in the XeF4 molecule?
|
|
Lone pairs |
Bonding pairs |
|
A. |
4 |
8 |
|
B. |
0 |
8 |
|
C. |
0 |
4 |
|
D. |
2 |
4 |
ANSWER
(Total 1 mark)
12. Explain why the bonds in silicon tetrachloride, SiCl4, are polar, but the molecule is not.
ANSWER
(Total 2 marks)
13. Which statement is correct about two elements whose atoms form a covalent bond with each other?
A. The elements are metals.
B. The elements are non-metals.
C. The elements have very low electronegativity values.
D. The elements have very different electronegativity values.
ANSWER
(Total 1 mark)
14. The compounds Na2O, Al2O3 and SO2 respectively are
A. acidic, amphoteric and basic.
B. amphoteric, basic and acidic.
C. basic, acidic and amphoteric.
D. basic, amphoteric and acidic.
ANSWER
(Total 1 mark)
15. (i) Describe three similarities and one difference in the reactions of lithium and potassium with water.
ANSWER
(4)
(ii) Give an equation for one of these reactions. Suggest a pH value for the resulting solution, and give a reason for your answer.
ANSWER
(3)
(Total 7 marks)
16. Discuss the acid-base nature of the period 3 oxides. Write an equation to illustrate the reaction of one of these oxides to produce an acid, and another equation of another of these oxides to produce a hydroxide.
ANSWER
(Total 5 marks)
17. Which compound of an element in period 3 reacts with water to form a solution with a pH greater than 7?
A. SiO2
B. SiCl4
C. NaCl
D. Na2O
ANSWER
(Total 1 mark)