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- Name any two ores of lead.(Solved)
Name any two ores of lead.
Date posted: May 17, 2019. Answers (1)
- a)Write down the electron arrangement for an atom of element U which has a mass number 14 and
contains 8 neutrons.(Solved)
a)Write down the electron arrangement for an atom of element U which has a mass number 14 and
contains 8 neutrons.
(b) Draw the structure of an atom of A given in (a) above.
Date posted: May 17, 2019. Answers (1)
- A sealed glass tube containing 250 cm3 of nitrogen gas at r.t.p was immersed in boiling water. Calculate the pressure inside the tube if the...(Solved)
A sealed glass tube containing 250 cm3 of nitrogen gas at r.t.p was immersed in boiling water. Calculate the pressure inside the tube if the volume of the gas does not change due to expansion of glass. (Room pressure=760mmHg, room temperature=298K).
Date posted: May 17, 2019. Answers (1)
- Explain this observation:
When hydrogen chloride gas is dissolved in water, the solution conducts electricity while a
solution of hydrogen chloride gas in propanone does not conduct...(Solved)
Explain this observation:
When hydrogen chloride gas is dissolved in water, the solution conducts electricity while a
solution of hydrogen chloride gas in propanone does not conduct electricity
Date posted: May 17, 2019. Answers (1)
- A solution of bromine in methyl benzene turns colourless when butane gas is passed through it.(Solved)
A solution of bromine in methyl benzene turns colourless when butane gas is passed through it.
(a) What type of reaction takes place?
(b) Write equation of the reaction which takes place.
Date posted: May 17, 2019. Answers (1)
- The thermochemical equation below shows a dynamic equilibrium between hydrogen iodide
gas and its elements:(Solved)
The thermochemical equation below shows a dynamic equilibrium between hydrogen iodide
gas and its elements:
(a) Explain how the following changes would affect the production of hydrogen iodide.
(i) increase in temperature
(ii) decrease in pressure.
(b) Calculate the molar enthalpy for formation of HI (g).
Date posted: May 17, 2019. Answers (1)
- 60 cm3 of ozone (O3) diffused through a semi permeable membrane in 80 seconds. Calculate the time taken for 90 cm3 of nitrogen (IV) oxide...(Solved)
60 cm3 of ozone (O3) diffused through a semi permeable membrane in 80 seconds. Calculate the time taken for 90 cm3 of nitrogen (IV) oxide (NO2) to diffuse under the same conditions. (O=16,N=14).
Date posted: May 17, 2019. Answers (1)
- When a current of 2.0 amperes was passed through a cell containing aqueous solution of T2+
ions of metal T for 9 minutes the mass of...(Solved)
When a current of 2.0 amperes was passed through a cell containing aqueous solution of T2+
ions of metal T for 9 minutes the mass of the cathode increased by 0.36g.(1Faraday=96,500coulombs)
(a) Calculate the quantity of electricity used.
(b) Determine the relative atomic mass of metal T.
(c) Explain whether metal T is less or more reactive than hydrogen gas.
Date posted: May 17, 2019. Answers (1)
- In an experiment 1.2g of granulated zinc were reacted with excess 2.0M sulphuric acid. The
time taken for the reaction to be completed was recorded. The...(Solved)
In an experiment 1.2g of granulated zinc were reacted with excess 2.0M sulphuric acid. The
time taken for the reaction to be completed was recorded. The experiment was repeated using
1.2g of zinc powder.
(a) In which experiment was the time taken shorter? Explain your answer.
(b) The mass of remaining mass of zinc was measured as time moved until when the
reaction was over. Sketch on the set of axes and label the two curves obtained that
would represent the mass of the remaining zinc
Experiment I represents granulated zinc.
Experiment II represents zinc powder.
Date posted: May 17, 2019. Answers (1)
- The set up below was used by a student. Filter paper soaked in purple litmus solution was
placed in the middle of the combustion tube.(Solved)
The set up below was used by a student. Filter paper soaked in purple litmus solution was
placed in the middle of the combustion tube.
(i) What is the main aim of the experiment.
(ii) State the first observation likely to have been made in the tube. Explain the observation.
Date posted: May 17, 2019. Answers (1)
- 0.5g of Manganese (IV) oxide were added to 50 cm3 of 3.5M hydrogen peroxide. The
temperature of the solution rose from 21oC to 64oC. The information...(Solved)
0.5g of Manganese (IV) oxide were added to 50 cm3 of 3.5M hydrogen peroxide. The
temperature of the solution rose from 21oC to 64oC. The information was represented on an energy level diagram as shown.
(a) Determine the number of moles of hydrogen peroxide that decomposed.
(b) Calculate the molar enthalpy of decomposition of hydrogen peroxide.
(c) On the same set of axes above sketch the curve that would be obtained if manganese (IV)
oxide was not used and other conditions remained constant.
Date posted: May 17, 2019. Answers (1)
- In a reaction, an alkanol B was converted to pent-2-ene(Solved)
In a reaction, an alkanol B was converted to pent-2-ene
(a) Give the structural formula of alkanol B.
(b) Name (i) the type of reaction that converts alkanol B to pent-2-ene.
(ii) The reagent used.
Date posted: May 17, 2019. Answers (1)
- The diagram below is a set up used to investigate the effect of heat on hydrated copper(II)
sulphate. Study the diagram and answer the questions that...(Solved)
The diagram below is a set up used to investigate the effect of heat on hydrated copper(II)
sulphate. Study the diagram and answer the questions that follow.
(a) Why is boiling tube slanted as shown?
(b) What is observed in the boiling tube.
(c) Identify liquid G.
Date posted: May 17, 2019. Answers (1)
- Explain why the following combination of reagents is unsuitable for the laboratory
preparation of hydrogen.(Solved)
Explain why the following combination of reagents is unsuitable for the laboratory
preparation of hydrogen.
(i) Zinc + dilute nitric acid.
(ii) Lead + dilute hydrochloric acid.
(iii) Potassium + dilute sulphuric acid.
Date posted: May 17, 2019. Answers (1)
- Give names of the following processes used to:
(Solved)
Give names of the following processes used to:
(a) Obtain a solvent from a saturated solution.
(b) Remove steam from air
(c) Separate zinc carbonate from water
(d) Separate a mixture of nitrogen and helium.
Date posted: May 17, 2019. Answers (1)
- Describe a simple test that can be carried out in the laboratory to distinguish between manganese (IV) oxide and copper (II) oxide.(Solved)
Describe a simple test that can be carried out in the laboratory to distinguish between manganese (IV) oxide and copper (II) oxide.
Date posted: May 17, 2019. Answers (1)
- State three properties common to both ammonia and calcium hydroxide solutions but different
from solution of sulphur (IV) oxide in water.(Solved)
State three properties common to both ammonia and calcium hydroxide solutions but different
from solution of sulphur (IV) oxide in water.
Date posted: May 17, 2019. Answers (1)
- A current of 25 amps was passed through molten aluminium oxide for 36 hrs.Calculate the amount of aluminium deposited in kg.(Al = 27, IF =...(Solved)
A current of 25 amps was passed through molten aluminium oxide for 36 hrs.Calculate the amount of aluminium deposited in kg.(Al = 27, IF = 96500C)
Date posted: May 17, 2019. Answers (1)
- Aluminium is extracted from its ore by electrolysis method. The current required in the
process is 4,000 amperes. Study the diagram and answer the questions that...(Solved)
Aluminium is extracted from its ore by electrolysis method. The current required in the
process is 4,000 amperes. Study the diagram and answer the questions that follow.
(a) Name:
(i) Electrolyte A
(ii) Substance D
(iii) Electrode E
(b) Name the material from which the electrodes are made.
(c ) (i) Write the equation that produces aluminium metal.
(ii) Explain why E has to be replaced from time to time.
(iii) Why is cryolite added to the electrolyte before the process of electrolysis ?
Date posted: May 17, 2019. Answers (1)
- In an experiment to determine the molar heat of neutralization of hydrochloric acid
with sodium hydroride, students of Furaha Secondary school reacted 100cm3 of 1M
hydrochloric acid...(Solved)
In an experiment to determine the molar heat of neutralization of hydrochloric acid
with sodium hydroride, students of Furaha Secondary school reacted 100cm3 of 1M
hydrochloric acid with 50cm3 of 2M sodium hydroxide solution. They obtained the following results.
Initial temperature of acid = 25.00C
Initial temperature of base = 25.00C
Highest temperature reached
With the acid – alkali mixture = 34.00C
(a) Write an ionic equation for the neutralization reaction between hydrochloric acid
and sodium hydroxide.
(b ) Calculate :
(i) The change in temperature.
(ii) The amount of heat produced during the reaction.
( Specific heat capacity of solution = 4.2 kJkg-1k-1 )
(iii) The molar heat of neutralization of sodium hydroxide.
(c) Write the thermochemical equation for the reaction.
(d) Draw an energy level diagram for the reaction.
Date posted: May 17, 2019. Answers (1)