CHEMISTRY TOPICAL QUESTIONS AND ANSWERS

K.C.S.E Chemistry Q & A - MODEL 1995PP1QN12

29/5/2020

With reference to atomic number of one, explain why hydrogen can be placed in either group I and VII of the periodic table.

K.N.E.C Marking Scheme

Hydrogen forms compounds by losing one electron like group I elements or by gaining one electron like group VII element /Hydrogen has one electron in outermost shell.

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K.C.S.E Chemistry Q & A - MODEL 1995PP1QN11

29/5/2020

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K.C.S.E Chemistry Q & A - MODEL 1995PP1QN11

A Solution of chlorine in tetra chloromethane turns colourless when propene gas is bubble though it.

a) What type of reaction takes place? (1mk)
b) Write an equation for the above reaction (1mk)

K.N.E.C Marking Scheme

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K.C.S.E Chemistry Q & A - MODEL 1995PP1QN10

29/5/2020

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K.C.S.E Chemistry Q & A - MODEL 1995PP1QN10

In an experiment, rods of metals P, Q and R were cleaned with sand paper and placed in a beaker containing water. Another set of rods was also cleaned and placed in a beaker containing dilute acid. After placing the rods in the two liquids bubbles of gas were seen around some of the rods as shown in the diagrams below.

a) Why is it necessary to clean the rods with sand paper before dipping them into the liquids.
b) Arrange the three metals in order of their reactivity starting with the most reactive.

K.N.E.C Marking Scheme

a) To remove oxide coating which could inhibit reaction
b) ORP

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K.C.S.E Chemistry Q & A - MODEL 1995PP1QN08

25/5/2020

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kcse Chemistry 1995 questions and answers

The diagram below represents a set–up that can be used to prepare and collect oxygen.

a) Write an equation for the reaction that takes place (1mk)
b) What property of oxygen makes it possible for its collection as indicated by the diagram (1mk)
c) Explain why it is important not to collect any gas for the first few. Seconds of the experiment. (1mk)

knec answers

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K.C.S.E Chemistry Q & A - MODEL 1995PP1QN07

25/5/2020

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The curve below represents the variation of temperature with time when pure and impure samples of a solid were heated separately.

Which curve sows the variation in temperature for the pure solid? Explain (2mks)

knec answers

II-Because pure substances have sharp MP and BP as shown by the flat regions of curve II. (accept systematic) (2 mks)

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K.C.S.E Chemistry Q & A - MODEL 1995PP1QN06

25/5/2020

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The table below gives some properties of gases D and E.

a) Describe how you would obtain a sample of E from a mixture of gases D and E. (2 mks)
b) Suggest a possible identity of gas D. Give a reason for your answer. (1 mk)

knec answers

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K.C.S.E Chemistry Q & A - MODEL 1995PP1QN05

24/5/2020

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a) Name one natural fibre.
b) Give one advantage of synthetic fibres over natural fibres. (1mk)

KNEC ANSWERS

a) sisal/ Cotton/ wool/ silk /jule/hemp/fur/hair (1mk)
b) They are stronger than natural fibres/OR are not easily affected by chemicals/lasts longer /durable/ can be produced easily in a large scale therefore cheaper (Reject. Strong bonds) (1mk)

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K.C.S.E Chemistry Q & A - MODEL 1995PP1QN04

24/5/2020

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In an experiment, soap solution was added to three separate samples of water.
The table below shows the volumes of soap solution required to form lather with 1000cm³ of each sample of water before and after boiling.

a) Which water sample is likely to be soft? Explain. (2 mks)
c) Name the change in the volume of soap solution used in sample III (1 mks)

KNEC ANSWERS

a) II because it requires little soap to lather (2 mks)
b) III has temporary (½) hardness, which is removed by boiling (½) (1 mks)

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K.C.S.E Chemistry Q & A - MODEL 1995PP1QN03

24/5/2020

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Calculate the amount of calcium carbonate that would remain if 15.0g of calcium carbonate were reacted with 0.2 moles of hydrochloric acid.

(C = 12.0 = 1.60, Ca = 40.0)

KNEC ANSWERS

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K.C.S.E Chemistry Q & A - MODEL 1995PP1QN02

23/5/2020

Comments

When bromine gas reacts with aqueous sodium hydroxide, the equilibrium represented by the equation:

is established.
What observations would be made if a few drops of sulfuric acid were added to the equilibrium mixture? Explain.

KNEC ANSWERS

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K.C.S.E Chemistry Q & A - MODEL 1995PP1QN01

23/5/2020

Comments

The electron arrangement ions X^3- and Y^- are 2, 8, and 2, 8, 8 respectively.

(a) Write the electronic arrangement of the elements X and Y. (2 mks)
(b) Write the formula of the compound that would be formed between X and Y.

KNEC ANSWERS

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K.C.S.E Chemistry Q & A - MODEL 1995PP1QN12

With reference to atomic number of one, explain why hydrogen can be placed in either group I and VII of the periodic table.

K.C.S.E Chemistry Q & A - MODEL 1995PP1QN11

A Solution of chlorine in tetra chloromethane turns colourless when propene gas is bubble though it.

K.C.S.E Chemistry Q & A - MODEL 1995PP1QN10

K.C.S.E Chemistry Q & A - MODEL 1995PP1QN08

The diagram below represents a set–up that can be used to prepare and collect oxygen.

K.C.S.E Chemistry Q & A - MODEL 1995PP1QN07

The curve below represents the variation of temperature with time when pure and impure samples of a solid were heated separately.

Which curve sows the variation in temperature for the pure solid? Explain (2mks)

K.C.S.E Chemistry Q & A - MODEL 1995PP1QN06

The table below gives some properties of gases D and E.

K.C.S.E Chemistry Q & A - MODEL 1995PP1QN05

a) Name one natural fibre.
b) Give one advantage of synthetic fibres over natural fibres. (1mk)

K.C.S.E Chemistry Q & A - MODEL 1995PP1QN04

In an experiment, soap solution was added to three separate samples of water.
The table below shows the volumes of soap solution required to form lather with 1000cm³ of each sample of water before and after boiling.

K.C.S.E Chemistry Q & A - MODEL 1995PP1QN03

Calculate the amount of calcium carbonate that would remain if 15.0g of calcium carbonate were reacted with 0.2 moles of hydrochloric acid.

(C = 12.0 = 1.60, Ca = 40.0)

K.C.S.E Chemistry Q & A - MODEL 1995PP1QN02

When bromine gas reacts with aqueous sodium hydroxide, the equilibrium represented by the equation:

is established.
What observations would be made if a few drops of sulfuric acid were added to the equilibrium mixture? Explain.

K.C.S.E Chemistry Q & A - MODEL 1995PP1QN01

The electron arrangement ions X^3- and Y^- are 2, 8, and 2, 8, 8 respectively.

Chemistry Topics

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With reference to atomic number of one, explain why hydrogen can be placed in either group I and VII of the periodic table. ​

​A Solution of chlorine in tetra chloromethane turns colourless when propene gas is bubble though it.

The diagram below represents a set–up that can be used to prepare and collect oxygen.

The curve below represents the variation of temperature with time when pure and impure samples of a solid were heated separately.

Which curve sows the variation in temperature for the pure solid? Explain (2mks)

The table below gives some properties of gases D and E.

a) Name one natural fibre. b) Give one advantage of synthetic fibres over natural fibres. (1mk)

In an experiment, soap solution was added to three separate samples of water. The table below shows the volumes of soap solution required to form lather with 1000cm3 of each sample of water before and after boiling.

​Calculate the amount of calcium carbonate that would remain if 15.0g of calcium carbonate were reacted with 0.2 moles of hydrochloric acid.

(C = 12.0 = 1.60, Ca = 40.0)

When bromine gas reacts with aqueous sodium hydroxide, the equilibrium represented by the equation:

is established. What observations would be made if a few drops of sulfuric acid were added to the equilibrium mixture? Explain.

The electron arrangement ions X3- and Y- are 2, 8, and 2, 8, 8 respectively.

Chemistry Topics

Archives

Author

With reference to atomic number of one, explain why hydrogen can be placed in either group I and VII of the periodic table.

A Solution of chlorine in tetra chloromethane turns colourless when propene gas is bubble though it.

a) Name one natural fibre.
b) Give one advantage of synthetic fibres over natural fibres. (1mk)

In an experiment, soap solution was added to three separate samples of water.
The table below shows the volumes of soap solution required to form lather with 1000cm³ of each sample of water before and after boiling.

Calculate the amount of calcium carbonate that would remain if 15.0g of calcium carbonate were reacted with 0.2 moles of hydrochloric acid.

is established.
What observations would be made if a few drops of sulfuric acid were added to the equilibrium mixture? Explain.

The electron arrangement ions X^3- and Y^- are 2, 8, and 2, 8, 8 respectively.