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i)
– zinc glows
- Yellow solid when hot (and white when cool)
ii) To drive out air initially present in the tube
iii) Extinguishes/ puts off a burning splint with a pop sound
marto answered the question on September 17, 2019 at 07:25
- The figure below represents a section of the periodic table. Study it and answer the questions that follow. The letters do not represent the actual...(Solved)
The figure below represents a section of the periodic table. Study it and answer the questions that follow. The letters do not represent the actual symbols of elements.
a) i).What chemical family does element J belong to?
ii. Compare the reactivity of element C and H. Explain.
b)
i) Write the chemical formula of the chloride of element D
ii) Name the type of structure of the chloride in b(i) above.
c). State and explain the difference in atomic radius and ionic radius of element F
d). Using dots (.) and crosses (x) show how bonding occurs when element E and F react.
Date posted: September 17, 2019. Answers (1)
- At 200C NO2 ; N2O4 gases exist in equilibrium as shown in the equation below.(Solved)
At 200C NO2 ; N2O4 gases exist in equilibrium as shown in the equation below.
(a) What is the significance of the negative sign as in the equation above.
(b) State and explain the observations that would be made when
(i) A syringe containing the mixture was immersed in warm water.
(ii) The volume of the gaseous mixture in the syringe was increased.
Date posted: September 17, 2019. Answers (1)
- The flow chart below and answer the questions that follow.(Solved)
The flow chart below and answer the questions that follow.
i). Identify the following;
Gas R
Solid M
Gas J
Liquid S
ii. Write a chemical equation for the formation of gas T
iii. Name catalyst K
iv) State two uses of liquid S
Date posted: September 17, 2019. Answers (1)
- An experiment was set as shown below(Solved)
An experiment was set as shown below
(a) Name the gas F
(b) State one physical characteristic of gas F.
(c ) What would be observed if a litmus paper was put in a solution of gas F.
Date posted: September 17, 2019. Answers (1)
- The table below shows the observations made on tests carried out on a colourless liquid sample.(Solved)
The table below shows the observations made on tests carried out on a colourless liquid sample.
(a) Identify (i) Cation in the sample
(ii) Anion in the sample
(b) Write the ionic equation for the reaction taking place in experiment (III).
Date posted: September 17, 2019. Answers (1)
- Study the flow chart below and answer the question that follow.(Solved)
Study the flow chart below and answer the question that follow.
(a) Identify substances P and Q
(b) What name is given to the type of reaction in step 2 ?
Date posted: September 17, 2019. Answers (1)
- The data below was recorded when metal K was completely burnt in air. K is not the actual symbol of the metal.
(R.A.M; K = 56,...(Solved)
The data below was recorded when metal K was completely burnt in air. K is not the actual symbol of the metal.
(R.A.M; K = 56, O = 16 )
Mass of empty crucible and lid = 10.240g
Mass of crucible, lid and metal K = 10.352g
Mass of crucible, lid and metal oxide = 10.400g
(a) Determine the mass of
(i) Metal K
(ii) Oxygen
(b) Determine the empirical formula of the metal oxide.
Date posted: September 17, 2019. Answers (1)
- 60cm3 of oxygen gas diffused through a porous partition in 50 seconds. How long will it take 120cm3 of sulphur (IV) oxide gas to diffuse...(Solved)
60cm3 of oxygen gas diffused through a porous partition in 50 seconds. How long will it take 120cm3 of sulphur (IV) oxide gas to diffuse through the same partition under the same conditions.
Date posted: September 17, 2019. Answers (1)
- In an experiment magnesium ribbon was reacted with dilute sulphuric (VI) acid and the volume of hydrogen gas produced with time noted. The graph below...(Solved)
In an experiment magnesium ribbon was reacted with dilute sulphuric (VI) acid and the volume of hydrogen gas produced with time noted. The graph below shows the volume of gas produced with time
Explain the following observations.
(i) The curve of the graph is steepest at the beginning.
(ii) The curve of the graph completely flattens at region AB.
(iii) On the same axis plot the curve that would be obtained if the acid used was ethanoic acid. Label it ethanoic acid
Date posted: September 17, 2019. Answers (1)
- The equation below represents a redox reaction.(Solved)
The equation below represents a redox reaction.
2FeCl2 (aq) + Cl2 (g)----->2FeCl3 (aq)
Identify the oxidizing agent. Give a reason.
Date posted: September 17, 2019. Answers (1)
- The table below gives the solubility of potassium bromide and potassium sulphate at 00C and 800C.(Solved)
The table below gives the solubility of potassium bromide and potassium sulphate at 00C and 800C.
When an aqueous mixture containing 60g of potassium bromide and 7g of potassium sulphate in 100g of water was cooled from 800C to 00C, some crystals were formed.
(a) Identify the crystals.
(b) Determine the mass of crystals formed.
(c) Name the method used to obtain the crystals.
Date posted: September 17, 2019. Answers (1)
- Describe how solid Aluminium chloride can be separated from a solid mixture of sodium chloride and ammonium chloride.(Solved)
Describe how solid Aluminium chloride can be separated from a solid mixture of sodium chloride and ammonium chloride.
Date posted: September 17, 2019. Answers (1)
- The diagram below shows spots of pure substances A, B and C on a chromatography paper. Spot D is that of a mixture.
After development A,...(Solved)
The diagram below shows spots of pure substances A, B and C on a chromatography paper. Spot D is that of a mixture.
After development A, B and C were found to have moved 9cm, 4cm and 7cm respectively D has separated into two spots which moved 7cm and 9cm.
(a) On the diagram
(i) Using 5 units in the alongside scale to represent 1cm Show the position of all the spots after development.
(ii) Identify the substances present in mixture D.
Date posted: September 17, 2019. Answers (1)
- The relative atomic mass of an element is 10.28.(Solved)
The relative atomic mass of an element is 10.28, it has two isotopes 
Calculate the relative percentage abundance of each isotope.
Date posted: September 17, 2019. Answers (1)
- The atomic number of Q and R are 9 and 17 respectively. Compare the electron affinity of Q and . Explain.(Solved)
The atomic number of Q and R are 9 and 17 respectively. Compare the electron affinity of Q and . Explain.
Date posted: September 17, 2019. Answers (1)
- In order to determine the molar heat of neutralization of 1M potassium hydroxide, 200cm³ of 1M hydrochloric acid both at the same temperature were mixed...(Solved)
In order to determine the molar heat of neutralization of 1M potassium hydroxide, 200cm³ of 1M hydrochloric acid both at the same temperature were mixed and stirred continuously with a thermometer. The temperature of the resulting solution was recorded after every 30 seconds until the highest temperature of the solution was attained.
(a) (i) Why was it necessary to stir the mixture of the two solutions?
(ii) Write an ionic equation for the reaction.
(b) The initial temperature for both solution was 24.5°C and the highest temperature attained by the mixture was 30.9°C. Calculate the
(i) heat change for the reaction.
(Specific heat capacity of the solution is 
Density of the solution is 
The volume of KOH used was 200cm³.
(ii) molar heat of the neutralisation.
(c) If ammonium hydroxide was used instead of potassium hydroxide the heat of neutralization would be different from the one obtained in b(ii) above.
Explain the difference.
(d) Draw an energy level diagram for the reaction between potassium hydroxide and hydrochloric acid.
Date posted: September 16, 2019. Answers (1)
- Explain why lead carbonate is not reacted with dil. H2SO4 in preparation of carbon (IV) oxide in the laboratory.(Solved)
Explain why lead carbonate is not reacted with dil. H2SO4 in preparation of carbon (IV) oxide in the laboratory.
Date posted: September 16, 2019. Answers (1)
- The table below shows ammeter readings obtained where different electrolytes of the same concentration were tested.(Solved)
The table below shows ammeter readings obtained where different electrolytes of the same concentration were tested.
Explain why ethanoic acid gave a lower ammeter reading the copper (II) sulphate solution.
Date posted: September 16, 2019. Answers (1)
- Study the scheme given below and answer the questions that follow.(Solved)
Study the scheme given below and answer the questions that follow.
(i) Write an equation for the reaction between propan-l-ol and potassium metal.
(ii) Name process I and II.
(iii) Identify the products A and B.
(iv) Name one catalyst used in Process II.
(v) Draw the structural formula of the repeating unit in the polymer C.
(vi) Write the structural formula of 2, 3-dichloropropene.
Date posted: September 16, 2019. Answers (1)
- In which homologous series does CH3 CH2 COOH belong?
(Solved)
In which homologous series does CH3 CH2 COOH belong?
Date posted: September 16, 2019. Answers (1)