a) Ammonia gas
b) Filtration
c) $2NaHCO_3(s) \rightarrow Na_2CO_3(s) + CO_2(g) + H_2O(g)$
johnmulu answered the question on April 10, 2017 at 14:02
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The diagram below represents a charcoal burner. Study it and answer the question that follows:
Date posted: April 10, 2017. Answers (1)
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A student investigated the effect of an electric current by passing it through some substances. The student used inert electrodes, and connected a bulb to the circuit. The table below shows the substances used and their states.
a) In which experiment did the bulb not light?
b) Explain your answer in (a) above.
Date posted: April 10, 2017. Answers (1)
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An electric current was passed through several substances and the results obtained recorded in the table below.
Which of these substances is likely to be:
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b) Hexane
c) Lead (II) bromide
Date posted: April 10, 2017. Answers (1)
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In an experiment to investigate the conductivity of substances, a student used the set-up shown below.
Date posted: April 10, 2017. Answers (1)
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Study the set-up below and answer the question that follows.
State and explain the observations that would be made when the circuit is completed
Date posted: April 10, 2017. Answers (1)
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(i) In which period of the periodic table is element A2? Give a reason.
ii) Explain why the atomic radius of:
I. A1 is greater than that of A2;
II. A4 is smaller than its ionic radius.
iii) Select the element which is in the same group as A3.
Date posted: April 10, 2017. Answers (1)
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ii) What observations would be made in step V? Give a reason.
iii) Explain why the total volume of hydrogen gas produced in step 1 was found to be very low although calcium and solution D were in excess.
iv) State one use of substance E.
b) Starting with solid sodium chloride, describe how pure sample of lead (II) chloride can be prepared in the laboratory.
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ii) Name another substance that can be used to dry chlorine gas.
Date posted: April 10, 2017. Answers (1)
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The diagram below illustrates a method of preparing salts by direct synthesis.
a) This method can be used to prepare either aluminium chloride or iron (III) chloride. Explain why it cannot be used to prepare sodium chloride.
b) Describe how a sample of sodium can be prepared in the laboratory by direct synthesis.
Date posted: April 10, 2017. Answers (1)
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i) Potassium ii) Silver
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Date posted: April 10, 2017. Answers (1)
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Identify
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b) Solid L
c) Gas M
Date posted: April 10, 2017. Answers (1)
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a) Identify the solids H and J
b) State one commercial use of solid J.
Date posted: April 10, 2017. Answers (1)
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The set-up below was used to prepare anhydrous chlorides of elements in laboratory where no fume cupboard was available. The chlorides were to be collected in flask 1.
The following table shows the melting and boiling points of the chlorides that were prepared.
a) Explain why it is necessary to pass dry chlorine through the apparatus before heating each element.
b) Give two reasons why tubes II and III were filled with soda lime (solid mixture of sodium hydroxide and calcium hydroxide)
c) Explain why it would not be possible to collect any sodium chloride in flask 1
d) Name one other substance that can be used in tubes II and III
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Date posted: April 10, 2017. Answers (1)
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a) Which is the most reactive non-metallic element shown
b) (i) Write the formula of the compound formed when element A
ii) Name the bond type in the compound formed in b (i) above.
c) i) What is the name given to the group of elements where C, G and H belong?
ii) Write the equation for the reaction that occurs when C in gaseous form is passed through a solution containing ions of element H.
d) The melting points of elements F and G are 1410oC and -101oC respectively. In terms of structure and bonding, explain why there is a large difference in the melting points of F and G.
e) D forms two oxides. Write the formula of each of the two oxides.
Date posted: April 10, 2017. Answers (1)
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b) The table below gives the number of electrons, protons and neutrons in particles
A, B, C, D, E, F and G.
(Solved)
a) Other than their location in the atom, name two other differences between an electron and a proton.
b) The table below gives the number of electrons, protons and neutrons in particles
A, B, C, D, E, F and G.
i) Which particle is likely to be a halogen?
ii) What is the mass number of E?
iii) Write a formula of the compound formed when E combines with G.
iv) Name the type of bond formed in (iii) above.
v) How does the radii of C and E compare? Give a reason.
vi) Draw a dot (.) and cross (x) diagram for the compound formed between A and F
vii) Why would particle B not react with particle D?
Date posted: April 10, 2017. Answers (1)
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a) Name the types of bonds that exists in the molecule
b) How many electrons are used for bonding in the molecule?
Date posted: April 10, 2017. Answers (1)
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Date posted: April 10, 2017. Answers (1)
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The table below gives atomic numbers of elements represented by the letters A, B, C and D.
Use the information to answer the questions that follow.
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b) Select the letter which represents the best oxidizing agent. Give a reason for your answer.
Date posted: April 10, 2017. Answers (1)
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The diagram below is a section of a model of the structure of element T.
a) State the type of bonding that exists in T.
b) In which group of the periodic table does element T belong? Give a reason.
Date posted: April 10, 2017. Answers (1)
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Date posted: April 10, 2017. Answers (1)
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The table below shows the properties of substances K, L, M and N.
Date posted: April 10, 2017. Answers (1)