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a) Manganese (IV) oxide
b) 2H2O2(l) $\rightarrow$ 2H2O(l) + O2(g)
c) – Welding. – Fuel in rockets - Breathing aid in hospitals – Steel making
johnmulu answered the question on April 6, 2017 at 12:11
- The oxides of elements A and B have the properties shown in the table below. (the letters do not represent the actual symbols of elements)(Solved)
The oxides of elements A and B have the properties shown in the table below. (the letters do not represent the actual symbols of elements)
Give one example of elements A and B
Date posted: April 6, 2017. Answers (1)
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Date posted: April 6, 2017. Answers (1)
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In an experiment a certain volume of air was passed repeatedly from syringe to syringe over heated excess zinc powder as shown in the diagram below.
The experiment was repeated using excess magnesium powder. In which of two experiments was the change in the volume of air greatest? Give reasons.
Date posted: April 6, 2017. Answers (1)
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State and explain two observations that would be made at the end of the experiment.
Date posted: April 6, 2017. Answers (1)
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The diagram below represents a set-up that can be used to prepare and collect oxygen
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Date posted: April 6, 2017. Answers (1)
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A student added very dilute sulphuric (VI) acid to four substances and recorded the observations shown in the table below.
For which tests are the observations wrong? Explain.
Date posted: April 6, 2017. Answers (1)
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Write an equation for each of the two reactions that takes place in the experiment represented by the diagram
Date posted: April 6, 2017. Answers (1)
- a) Explain what happens to the molecules of water in the region BC in terms of Kinetic theory.
b) In what state is the water in the region DE?
(Solved)
The graph below is a cooling curve for water. Study it and answer the questions that follow.
a) Explain what happens to the molecules of water in the region BC in terms of Kinetic theory.
b) In what state is the water in the region DE?
Date posted: April 6, 2017. Answers (1)
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The set up below was used to separate a mixture of methanol and propanol. Study it and answer the questions that follow.
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Date posted: April 6, 2017. Answers (1)
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The chromatogram below was obtained from a contaminated food sample P. Contaminants Q,R,S and T are suspected to be in P. Use it to answer the following questions.
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b) Which is the most soluble contaminant in P?
Date posted: April 6, 2017. Answers (1)
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Date posted: April 6, 2017. Answers (1)
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Give the name of the: a) Process taking place between to and t1
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Date posted: April 6, 2017. Answers (1)
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Sample of urine from three participants F, G and H at an international sports meeting were spotted onto a chromatography paper alongside two from illegal drugs A1 and A2. A chromatogram was run using methanol. The figure below shows the chromatogram.
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Date posted: April 6, 2017. Answers (1)
- The graph below shows a curve obtained when water at 20o was heated for 15 minutes.(Solved)
The graph below shows a curve obtained when water at 20o was heated for 15 minutes.
a) What happens to the water molecules between points W and X?
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c) Explain why the temperature does not rise between points X and Y.
Date posted: April 6, 2017. Answers (1)
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a) Study the properties of substances V2 and V4 in the table below and answer the questions that follows.
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Date posted: April 6, 2017. Answers (1)
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A piece of chromatography paper was spotted with coloured inks obtained from pens labeled 1 to 6. The diagram below show the spots after the chromatogram was developed.
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Date posted: April 5, 2017. Answers (1)
- The set-Up below represents the apparatus that may be used to separate a mixture of two miscible liquids C and D whose boiling points are 80oC and 110oC.(Solved)
The set-Up below represents the apparatus that may be used to separate a mixture of two miscible liquids C and D whose boiling points are 80oC and 110oC.
a) Name B
b) What is the purpose of the thermometer?
c) Which liquid was collected in the test tube?
Date posted: April 5, 2017. Answers (1)
- The diagram below shows the relationships between the physical state of matter. Study it and answer the questions that follow.(Solved)
The diagram below shows the relationships between the physical state of matter. Study it and answer the questions that follow.
a) Identify the processes R, V, W and U.
b) Name one substance which can undergo the process represented by S and T
c) Explain whether process W is exothermic or endothermic
Date posted: April 5, 2017. Answers (1)
- In an experiment to separate a mixture of two organic liquids, Liquid M (b.p 56oC) and liquid N (b.p.118oC), a student set up the apparatus shown below(Solved)
In an experiment to separate a mixture of two organic liquids, Liquid M (b.p 56oC) and liquid N (b.p.118oC), a student set up the apparatus shown below
a) Identify two mistakes in the set-up.
b) What method would the student use to test the purity of the distillates obtained?
Date posted: April 5, 2017. Answers (1)
- The curve below represents the variation of temperature with time pure and impure samples of a solid were heated separately.(Solved)
The curve below represents the variation of temperature with time pure and impure samples of a solid were heated separately.
Which curve shows the variation in temperature for pure solid? Explain.
Date posted: April 5, 2017. Answers (1)