i) K – potassium
ii) Cl – chlorine
iii) Fe – iron
iv) Mg – magnesium.
v) C – carbon
vi) Be – beryllium.
marto answered the question on October 1, 2019 at 09:12
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Distinguish between temporary physical and permanent chemical changes.
(Solved)
Distinguish between temporary physical and permanent chemical changes.
Date posted:
October 1, 2019
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Answers (1)
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The graph below shows the shape of the curve obtained by a student when solid X was heated to boiling.
(Solved)
The graph below shows the shape of the curve obtained by a student when solid X was heated to boiling.
a) Determine the melting point of solid X.
b) After the experiment the student concluded that substance x was pure substance. Explain why he concluded so.
c) If candle wax was used in the above experiment the portion QR would be horizontal. What does this tell us about candle wax?
Date posted:
October 1, 2019
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Answers (1)
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Identify the elements present in the following compounds.
i) Magnesium oxide.
ii) Zinc chloride
iii) Sodium sulphate.
iv) Aluminium nitrate
(Solved)
Identify the elements present in the following compounds.
i) Magnesium oxide.
ii) Zinc chloride
iii) Sodium sulphate.
iv) Aluminium nitrate
Date posted:
October 1, 2019
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Answers (1)
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Study the diagram below and answer the question that follows.
(Solved)
Study the diagram below and answer the question that follows.
a) Name the process labeled a, b, c and d.
b) Draw a similar diagram to show the effect of temperature on solid carbon (IV) oxide (dry ice)
Date posted:
October 1, 2019
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Answers (1)
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State two ways of preventing drug abuse.
(Solved)
State two ways of preventing drug abuse.
Date posted:
October 1, 2019
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Answers (1)
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Explain why molten calcium chloride conducts electricity while silicon (IV) oxide does not.
(Solved)
Explain why molten calcium chloride conducts electricity while silicon (IV) oxide does not.
Date posted:
October 1, 2019
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Answers (1)
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Phosphorus element smoulders in air to form two oxides
(a) Name the two oxides
(b) State the nature of the solution when the above mentioned oxides are...
(Solved)
Phosphorus element smoulders in air to form two oxides
(a) Name the two oxides
(b) State the nature of the solution when the above mentioned oxides are dissolved in water.
Date posted:
October 1, 2019
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Answers (1)
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Soot is one of the environmental pollutants.
(i) Explain the term pollutant
(ii) State how soot is formed from hydrocarbons
(Solved)
Soot is one of the environmental pollutants.
(i) Explain the term pollutant
(ii) State how soot is formed from hydrocarbons
Date posted:
October 1, 2019
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Answers (1)
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The diagrams below are some common laboratory apparatus. Name each apparatus and state its use.
(Solved)
The diagrams below are some common laboratory apparatus. Name each apparatus and state its use.
Date posted:
October 1, 2019
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Answers (1)
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(a) What name is given to the two types of atoms.
(Solved)
(a) What name is given to the two types of atoms.
Date posted:
October 1, 2019
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Answers (1)
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Oxygen is obtained on large scale by the fractional distillation of air as shown on the flow chart below.
(Solved)
Oxygen is obtained on large scale by the fractional distillation of air as shown on the flow chart below.
a) Explain why air is considered as a mixture
b) Identify the substance that is removed at the filtration stage
c) Explain why Carbon (IV) oxide and water are removed before liquefaction of air
d) Identify the component that is collected at -186°C
Date posted:
October 1, 2019
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Answers (1)
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In temperate countries, salt is sprayed on roads to defrost and clear roads but the long term effect on this practice is costly to motorist.
(a)...
(Solved)
In temperate countries, salt is sprayed on roads to defrost and clear roads but the long term effect on this practice is costly to motorist.
(a) Explain the role of salt in defrosting the ice.
(b) Explain why the long term effect is costing to motorist.
Date posted:
October 1, 2019
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Answers (1)
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Study the table below.
(Solved)
Study the table below.
(a) Which elements belong to the same period of the periodic table?
(b) What is the formula of the compound formed by L and N.?
(c) Compare the atomic and ionic radii of element L.
Date posted:
October 1, 2019
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Answers (1)
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A student set-up the apparatus below in order to determine the percentage by volume of oxygen in air.
(Solved)
A student set-up the apparatus below in order to determine the percentage by volume of oxygen in air.
a) Why did water rise when the reaction had stopped?
b) The student wrote the expression for the percentage by volume of oxygen in air as
Why was the volume of oxygen calculated using the above expression incorrect?
c) What should have been done after the reaction had stopped in order to get a correct volume.
Date posted:
October 1, 2019
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Answers (1)
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Two solutions J and K were tested with blue litmus papers and methyl orange indicator.
Blue litmus remained blue in both solutions. Methyl orange remained...
(Solved)
Two solutions J and K were tested with blue litmus papers and methyl orange indicator.
Blue litmus remained blue in both solutions. Methyl orange remained orange in K but turned yellow in J.
(a) What is the nature of substance J? Explain.
(b) Give an example of a substance that K is likely to be.
Date posted:
October 1, 2019
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Answers (1)
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State with reasons whether the changes below are physical or chemical.
(Solved)
State with reasons whether the changes below are physical or chemical.
Date posted:
October 1, 2019
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Answers (1)
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Describe how the following reagents can be used to prepare copper (II) hydroxide, solid copper (II) sulphate, solid sodium hydroxide and distilled water
(Solved)
Describe how the following reagents can be used to prepare copper (II) hydroxide, solid copper (II) sulphate, solid sodium hydroxide and distilled water.
Date posted:
October 1, 2019
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Answers (1)
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Complete the table below for the characteristics of the sub atomic particles.
(Solved)
Complete the table below for the characteristics of the sub atomic particles.
Date posted:
October 1, 2019
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Answers (1)
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The flow chart below illustrates two industrial processes, Haber process and the Contact process:
(Solved)
The flow chart below illustrates two industrial processes, Haber process and the Contact process:
(a) (i) Give the name of the process by which air is seperated into oxygen and nitrogen
(i) Apart from oxygen and nitrogen gases produced from process (a)(i) name one other gas produced
(b) Name the substances represented by the letters A, B, C and D
(c) Name the catalysts used in:
(i) Haber Process
(ii) Contact Process
(d) Explain the role of the catalysts in both the Haber and the Contact processes
(e) Write a chemical equation for the formation of compound B
(f) Calculate the percentage by mass of the nitrogen present in compound D
(g) Give one major use of compound D
Date posted:
October 1, 2019
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Answers (1)
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Study the set-up below and answer the questions that follow.
(Solved)
Study the set-up below and answer the questions that follow.
a) (i) Name Gas X
(ii) State the effect of releasing gas X to the environment
b) Write down equations for the reactions taking place in;
(i) Tube I
(ii) Tube II
(iii) Flask
c) State the observation made in tube III
d) Write down an equation for the reaction which could be used to generate Carbon (IV) Oxide for the above set up
(e) Name the reagents used to generate gas X in the laboratory
(f) Complete the diagram above to show how excess gas X can be collected
Date posted:
October 1, 2019
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Answers (1)