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- Radioactive polonium -216 decays as shown below.(Solved)
Radioactive polonium -216 decays as shown below.
(i) Find the value of M and N.
(ii) If after 112 days 
of Polonium remained, calculate the half-life of polonium.
Date posted: September 25, 2019. Answers (1)
- Zinc metal can be used in the laboratory to prepare hydrogen gas from an appropriate mineral acid while copper metal cannot.
Explain.(Solved)
Zinc metal can be used in the laboratory to prepare hydrogen gas from an appropriate mineral acid while copper metal cannot.
Explain.
Date posted: September 24, 2019. Answers (1)
- How would the following pair of compounds be chemically distinguished? CH3COOH and CH3CH2OH.(Solved)
How would the following pair of compounds be chemically distinguished? CH3COOH and CH3CH2OH.
Date posted: September 24, 2019. Answers (1)
- Differentiate elaborately between Elements and Compounds(Solved)
Differentiate elaborately between Elements and Compounds.
Date posted: September 23, 2019. Answers (1)
- Calculate the number of Calcium atoms in 10g of calcium.
(Ca = 40, Avogadro number = 6.0 x 1023)(Solved)
Calculate the number of Calcium atoms in 10g of calcium.
(Ca = 40, Avogadro number = 6.0 x 1023)
Date posted: September 23, 2019. Answers (1)
- Your friend’s clothes have caught fire. In order to extinguish the fire you decide to cover with a damp blanket. (Solved)
Your friend’s clothes have caught fire. In order to extinguish the fire you decide to cover with a damp blanket. What is the purpose of the damp blanket?
Date posted: September 23, 2019. Answers (1)
- The flow chart below shows a series of reactions starting withpropan-l-ol. Study it and answer the questions that follow.(Solved)
The flow chart below shows a series of reactions starting withpropan-l-ol. Study it and answer the questions that follow.
(i) Name:
I. Process Y
II. Substances R and C
III. Process W
IV. Polymer X
(ii) Write a balanced chemical equation for the combustion of propane.
(iii) State one use of polymer X
Date posted: September 23, 2019. Answers (1)
- State how burning can be used to distinguish between prepane and propyne. Explain your answer.(Solved)
(a) State how burning can be used to distinguish between prepane and propyne. Explain your answer.
(b) Draw the structural formular of the 4th member of the homologous series in which propyne is a member
Date posted: September 23, 2019. Answers (1)
- Biogas is made from natural organic waste. A from four student set –up the apparatus below to investigate the composition of the gas. He passed...(Solved)
Biogas is made from natural organic waste. A from four student set –up the apparatus below to investigate the composition of the gas. He passed it over heated copper (II) oxide. After that he obtained two products. One was cooled in a boiling tube while the other was collected using a syringe.
(a) What is the function of calcium oxide
(b) Name product
i) P
ii) Y
(c) Give the two observations made in tube X
(d) i) Name the type of reaction taking place in tube X
ii) Write the equation for the reaction above in (d)(i)
(e) What elements are present in biogas
(f) Explain why one tube in boiling tube Q is longer than the other
Date posted: September 23, 2019. Answers (1)
- Using the following thermochemical equations draw an energy cycle diagram.(Solved)
Using the following thermochemical equations draw an energy cycle diagram.
(i) Name the heat of change represented by thermochemical equation A
(ii) Using thermochemical equations A, B, C. Calculate the molar heat of combustion of ethyne
(iii) Give 3 factors considered for choosing a good fuel
Date posted: September 23, 2019. Answers (1)
- The following are half-cell reactions and their reduction potentials
(i) Write the cell representation for the electrochemical cell that would give the highest E? value.
(ii)...(Solved)
The following are half-cell reactions and their reduction potentials
(i) Write the cell representation for the electrochemical cell that would give the highest Eθ value.
(ii) Give one industrial use of electrolysis
Date posted: September 23, 2019. Answers (1)
- Study the diagrams below.(Solved)
Study the diagrams below.
(a) State the observations made at I and II
(b) Write the equation to show the reactions at II if dry sulphur (IV) oxide was used in place of dry chlorine.
Date posted: September 20, 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
Process Y
i. Write the formula of Alcohol X, Compound Z and name process Y.
ii. Propane and Chlorine react as shown below :
a) Name the type of reaction that takes place.
b) State the condition under which this reaction takes place.
Date posted: September 20, 2019. Answers (1)
- Study the table below and answer the questions that follow(Solved)
Study the table below and answer the questions that follow
i) What name is given to a series of organic compounds like the ones in the table?
ii) To what class of organic compounds does the above hydrocarbon belongs?
iii) Select one hydrocarbon that would be a gas at room temperature (298K) given a reason for your answer.
iv) Give the formula of the seventh member of the above series.
v) What is the relationship between the boiling point and the relative molecular masses of the hydrocarbons in the table above?
Explain your answer.
Date posted: September 20, 2019. Answers (1)
- Study the scheme below and answer questions that follow.(Solved)
Study the scheme below and answer questions that follow.
i) Name
Gas K
Gas M
ii) State observation made in
Step I
Step II
iii) State the conditions necessary for step II to occur.
iv) Write an equation to show how pollution effect of sulphur (IV) oxide is controlled in contact process.
v) Explain the role of sulphur in vulcanization of rubber.
Date posted: September 20, 2019. Answers (1)
- Study the structure below and answer questions that follow.(Solved)
Study the structure below and answer questions that follow:
a) What observation is made when the molecule above is heated to a temperature of 1130 C
b) Write an equation for the reaction of atom of the above structure with hydrogen.
Date posted: September 20, 2019. Answers (1)
- Equal masses of magnesium ribbon were reacted separately with equal volumes of 1M hydrochloric acid and 1M methanoic acid. The results were plotted on a...(Solved)
Equal masses of magnesium ribbon were reacted separately with equal volumes of 1M hydrochloric acid and 1M methanoic acid. The results were plotted on a graph as shown below. Two curves X and Y were obtained.
a) Explain which curves represents:
i) 1M hydrochloric acid.
ii) 1M Methanoic acid.
b) State the significance of point Z.
c) Write ionic equation for the reaction between magnesium and dilute hydrochloric acid.
d) Calculate the maximum mass of the gas that would be liberated if 1.2g of magnesium reacted with excess hydrochloric acid.
(Mg = 24, H =1).
e) Calculate the volume of the gas produced in (e) above at r.t.p (molar gas volume at r.t.p) = 24dm3.
Date posted: September 20, 2019. Answers (1)
- The arrangements below shows a set-up to investigate the effect of an electric current on molten lead (II) iodide.(Solved)
The arrangements below shows a set-up to investigate the effect of an electric current on molten lead (II) iodide.
a) Identify two mistakes in the set-up.
b) State three observations made after correcting the mistakes.
c) What particles are responsible for electrical conductivity?
d) Write the equations for the reactions taking place at the electrodes.
e) Indicate on the diagram direction of flow of electric current.
Date posted: September 20, 2019. Answers (1)
- Study the information in the table below and answer the questions that follow, letters do not represent actual symbols of the element.(Solved)
Study the information in the table below and answer the questions that follow, letters do not represent actual symbols of the element.
a) Write the electronic configuration of an ion of elements T and U.
b) Why do the elements represented by R and S have two values of melting point.
c) Select an element:
i) Which is the most electronegative.
ii) That belongs to period 4, explain.
d) Explain why:
i) Ionic radius of R is bigger than its atomic radius.
ii) The atomic radius of L is bigger than that of R yet they are in the same period.
e) Using dots (.) and cross (x) to represent outermost electron show bonding in the compound formed between L and M.
f) Write an equation for the reaction that occurs between U and water.
g) Describe how a solid mixture of the sulphate of element N and lead (II) sulphate can be separated into solid sample of dry lead (II) sulphate.
Date posted: September 20, 2019. Answers (1)
- Study the set-up of apparatus below and answer the questions that follow.(Solved)
Study the set-up of apparatus below and answer the questions that follow.
a) State and explain the observation that would be made in tube L as the experiment progresses in the first few minutes.
Observation.
Explanation.
b) How would the observations in the tube L change if the experiment is carried out for a long time. Explain using a chemical equation.
Observation.
Equation.
c) State three observations made when liquid S is reacted with sodium metal.
d) State the use of the suction pump in this experiment.
Date posted: September 19, 2019. Answers (1)