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- Hydrogen burns in oxygen to form an oxide.
(i) Write an equation for the reaction
(ii) State two precautions that must be taken before the combustion begins...(Solved)
Hydrogen burns in oxygen to form an oxide.
(i) Write an equation for the reaction
(ii) State two precautions that must be taken before the combustion begins and at the end of
the combustion.
Date posted: October 1, 2019. Answers (1)
- Hydrogen can be prepared by reacting zinc with dilute hydrochloric acid.
a) Write an equation for the reaction.
b) Name an appropriate drying agent for hydrogen gas.
c)...(Solved)
Hydrogen can be prepared by reacting zinc with dilute hydrochloric acid.
a) Write an equation for the reaction.
b) Name an appropriate drying agent for hydrogen gas.
c) Explain why copper metal cannot be used to prepare hydrogen gas.
Date posted: October 1, 2019. Answers (1)
- Using dots(•) and crosses(x), show bonding in magnesium chloride. (Solved)
Using dots(•) and crosses(x), show bonding in magnesium chloride.
Date posted: September 27, 2019. Answers (1)
- Distinguish between simulation and virtual reality(Solved)
Distinguish between simulation and virtual reality
Date posted: September 26, 2019. Answers (1)
- Study the flow chart below and answer the questions that follow.(Solved)
Study the flow chart below and answer the questions that follow.
i) Name Compound T
ii) Gas U
iii) The equation below shows the reaction between sulphur (IV) oxide gas and oxygen gas to produce sulphur (VI) oxide in contact process.
2 SO2(g) + O2(g)----->2SO3 D = -197 kJ/mol
State two conditions that are necessary for maximum production of SO3.
iv) Name the catalyst used for this reaction.
Date posted: September 26, 2019. Answers (1)
- Study the reaction scheme below and use it to answer the questions that follow.(Solved)
Study the reaction scheme below and use it to answer the questions that follow.
i) Name the process in;
Step I
Step II
ii) State the reagent necessary for the process in
Step II
Step III
iii) Name the type of reaction taking place in step III
Date posted: September 26, 2019. Answers (1)
- Castor oil extracted from castor seeds is found to change the colour of acidified potassium manganate (VII) .
i) State the colour change.
ii) Explain why castor...(Solved)
Castor oil extracted from castor seeds is found to change the colour of acidified potassium manganate (VII) .
i) State the colour change.
ii) Explain why castor oil reacts with acidified Potassium manganate (VII) to cause the colour change.
Date posted: September 26, 2019. Answers (1)
- Name the following compounds.(Solved)
Name the following compounds.
Date posted: September 25, 2019. Answers (1)
- Below is a list of major components of crude oil and their boiling points.(Solved)
Below is a list of major components of crude oil and their boiling points.
i) What is the name of the process by which the constituents of crude oil can be separated?
ii) Give one use of the gases component.
iii) Give the order by which the components are obtained from the mixture, starting with the first.
Date posted: September 25, 2019. Answers (1)
- The chromatogram below was obtained from a plant extract. Use it to answer the questions that follow.(Solved)
The chromatogram below was obtained from a plant extract. Use it to answer the questions that follow.
i) Name line W
ii) What does the dotted line represent?
iii) State with a reason the least soluble dye in the moving solvent.
Date posted: September 25, 2019. Answers (1)
- The table below shows the results obtained when four solvents were used to separate a dye. Study the results and use them to answer the...(Solved)
The table below shows the results obtained when four solvents were used to separate a dye. Study the results and use them to answer the questions that follow.
i) Identify the most suitable solvent for this separation. Give a reason for your answer.
ii) What does the result of the solvent C tell us about the dye?
Date posted: September 25, 2019. Answers (1)
- A student wrongly categorised air as a compound and not as a mixture. Give two reasons as to why the student was wrong.(Solved)
A student wrongly categorised air as a compound and not as a mixture. Give two reasons as to why the student was wrong.
Date posted: September 25, 2019. Answers (1)
- Two hydrocarbons compounds are represented by the formulae C4H8 and C4H10
Which of the compounds is saturated;
Explain(Solved)
Two hydrocarbons compounds are represented by the formulae C4H8 and C4H10
Which of the compounds is saturated;
Explain
Date posted: September 25, 2019. Answers (1)
- Draw the following structure.
2-bromo-4-methylpent-2-ene
(Solved)
Draw the following structure.
2-bromo-4-methylpent-2-ene
Date posted: September 25, 2019. Answers (1)
- A compound was analysed and found to contain 24.27% carbonate, 4.08% hydrogen and the rest is chlorine. If the molar mass of the compound is...(Solved)
A compound was analysed and found to contain 24.27% carbonate, 4.08% hydrogen and the rest is chlorine. If the molar mass of the compound is 99.0, calculate the molecular formula.
(C = 12, H = 1, Cl = 25.5)
Date posted: September 25, 2019. Answers (1)
- The chromatogram below shows the constituents of a flower extract. Study it and answer the question that follows.(Solved)
The chromatogram below shows the constituents of a flower extract. Study it and answer the question that follows.
Give a reason to explain the different positions of red and yellow pigments.
Date posted: September 25, 2019. Answers (1)
- A mixture of substance K (density 0.626g/cm3) and Z (density 0.85g/cm3) was allowed to settle in a container as shown below.(Solved)
A mixture of substance K (density 0.626g/cm3) and Z (density 0.85g/cm3) was allowed to settle in a container as shown below.
a) Which liquid forms layer (I)
b) Explain your answer in (a) above.
Date posted: September 25, 2019. Answers (1)
- The table below is a part of the periodic table. The letters are not the actual symbols of the element. Study it and answer the...(Solved)
The table below is a part of the periodic table. The letters are not the actual symbols of the element. Study it and answer the questions that follow.
a) Select an element which is the most reactive.
b) How do the ionic radius of T and S compare? Explain.
Date posted: September 25, 2019. Answers (1)
- Half-life of a radio-active elements is 30 days. Calculate the time required for its activity 37.5 counts per minute.(Solved)
Half-life of a radio-active elements is 30 days. Calculate the time required for its activity 37.5 counts per minute.
Date posted: September 25, 2019. Answers (1)
- During an electrolysis of Zinc sulphate using inert electrodes, a current of 0.5A was passed for 40 minutes on a steady current.
a) Write down the...(Solved)
During an electrolysis of Zinc sulphate using inert electrodes, a current of 0.5A was passed for 40 minutes on a steady current.
a) Write down the equation at the cathode.
b) Calculate the volume produced at the cathode given that 1F = 96,500c, MGV = 22.4 litres.
Date posted: September 25, 2019. Answers (1)