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- Phosphorus element smoulders in air to form two oxides
(a) Name the two oxides
(b) State the nature of the solution when the above mentioned oxides are...(Solved)
Phosphorus element smoulders in air to form two oxides
(a) Name the two oxides
(b) State the nature of the solution when the above mentioned oxides are dissolved in water.
Date posted: October 1, 2019. Answers (1)
- Soot is one of the environmental pollutants.
(i) Explain the term pollutant
(ii) State how soot is formed from hydrocarbons(Solved)
Soot is one of the environmental pollutants.
(i) Explain the term pollutant
(ii) State how soot is formed from hydrocarbons
Date posted: October 1, 2019. Answers (1)
- The diagrams below are some common laboratory apparatus. Name each apparatus and state its use.(Solved)
The diagrams below are some common laboratory apparatus. Name each apparatus and state its use.
Date posted: October 1, 2019. Answers (1)
- (a) What name is given to the two types of atoms.(Solved)
(a) What name is given to the two types of atoms.
Date posted: October 1, 2019. Answers (1)
- Oxygen is obtained on large scale by the fractional distillation of air as shown on the flow chart below.(Solved)
Oxygen is obtained on large scale by the fractional distillation of air as shown on the flow chart below.
a) Explain why air is considered as a mixture
b) Identify the substance that is removed at the filtration stage
c) Explain why Carbon (IV) oxide and water are removed before liquefaction of air
d) Identify the component that is collected at -186°C
Date posted: October 1, 2019. Answers (1)
- In temperate countries, salt is sprayed on roads to defrost and clear roads but the long term effect on this practice is costly to motorist.
(a)...(Solved)
In temperate countries, salt is sprayed on roads to defrost and clear roads but the long term effect on this practice is costly to motorist.
(a) Explain the role of salt in defrosting the ice.
(b) Explain why the long term effect is costing to motorist.
Date posted: October 1, 2019. Answers (1)
- Study the table below.(Solved)
Study the table below.
(a) Which elements belong to the same period of the periodic table?
(b) What is the formula of the compound formed by L and N.?
(c) Compare the atomic and ionic radii of element L.
Date posted: October 1, 2019. Answers (1)
- A student set-up the apparatus below in order to determine the percentage by volume of oxygen in air.(Solved)
A student set-up the apparatus below in order to determine the percentage by volume of oxygen in air.
a) Why did water rise when the reaction had stopped?
b) The student wrote the expression for the percentage by volume of oxygen in air as
Why was the volume of oxygen calculated using the above expression incorrect?
c) What should have been done after the reaction had stopped in order to get a correct volume.
Date posted: October 1, 2019. Answers (1)
- Two solutions J and K were tested with blue litmus papers and methyl orange indicator.
Blue litmus remained blue in both solutions. Methyl orange remained...(Solved)
Two solutions J and K were tested with blue litmus papers and methyl orange indicator.
Blue litmus remained blue in both solutions. Methyl orange remained orange in K but turned yellow in J.
(a) What is the nature of substance J? Explain.
(b) Give an example of a substance that K is likely to be.
Date posted: October 1, 2019. Answers (1)
- State with reasons whether the changes below are physical or chemical.(Solved)
State with reasons whether the changes below are physical or chemical.
Date posted: October 1, 2019. Answers (1)
- Describe how the following reagents can be used to prepare copper (II) hydroxide, solid copper (II) sulphate, solid sodium hydroxide and distilled water(Solved)
Describe how the following reagents can be used to prepare copper (II) hydroxide, solid copper (II) sulphate, solid sodium hydroxide and distilled water.
Date posted: October 1, 2019. Answers (1)
- Complete the table below for the characteristics of the sub atomic particles.(Solved)
Complete the table below for the characteristics of the sub atomic particles.
Date posted: October 1, 2019. Answers (1)
- The flow chart below illustrates two industrial processes, Haber process and the Contact process:(Solved)
The flow chart below illustrates two industrial processes, Haber process and the Contact process:
(a) (i) Give the name of the process by which air is seperated into oxygen and nitrogen
(i) Apart from oxygen and nitrogen gases produced from process (a)(i) name one other gas produced
(b) Name the substances represented by the letters A, B, C and D
(c) Name the catalysts used in:
(i) Haber Process
(ii) Contact Process
(d) Explain the role of the catalysts in both the Haber and the Contact processes
(e) Write a chemical equation for the formation of compound B
(f) Calculate the percentage by mass of the nitrogen present in compound D
(g) Give one major use of compound D
Date posted: October 1, 2019. Answers (1)
- Study the set-up below and answer the questions that follow.(Solved)
Study the set-up below and answer the questions that follow.
a) (i) Name Gas X
(ii) State the effect of releasing gas X to the environment
b) Write down equations for the reactions taking place in;
(i) Tube I
(ii) Tube II
(iii) Flask
c) State the observation made in tube III
d) Write down an equation for the reaction which could be used to generate Carbon (IV) Oxide for the above set up
(e) Name the reagents used to generate gas X in the laboratory
(f) Complete the diagram above to show how excess gas X can be collected
Date posted: October 1, 2019. Answers (1)
- The grid below shows a part of the periodic table. The letters do not represent the actual symbols. Use it to answer the questions that...(Solved)
The grid below shows a part of the periodic table. The letters do not represent the actual symbols. Use it to answer the questions that follow:-
a) How do the atomic radius of element
(i) X and M compare. Explain.
(ii) U and Q. Explain
b) Which letter represent the most reactive metal. Explain.
Date posted: October 1, 2019. Answers (1)
- The number of protons, neutrons and electrons in atoms A to F are given in the table below the letters do not represent the actual...(Solved)
The number of protons, neutrons and electrons in atoms A to F are given in the table below the letters do not represent the actual symbol of the elements:-
Choose from the table the letters that represent:
(i) An atom of a metal
(ii) A neutral atom of a non-metal
(iii) An atom of a noble gas
(iv) A pair of isotopes
(v) A cation
(vi) Anion
Date posted: October 1, 2019. Answers (1)
- When zinc is heated to redness in a current of steam, hydrogen gas is obtained. Write an equation for the reaction(Solved)
When zinc is heated to redness in a current of steam, hydrogen gas is obtained. Write an equation for the reaction
Date posted: October 1, 2019. Answers (1)
- 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)