a. – The chromatogram must have different solubility rate.
- The dyes must have different adsorption on the filter paper.
b. – It is the furthest distance reached by the solvent on the adsorbent material (or filter paper).
- It is indicated as H on the diagram.
c. Red, blue and green.
. B – It remains on the baseline
. Dye A and C
. They have only one chromatogram.
d – Detecting and identifying poisonous substances present in food substances.
- Separation of dyes into pure colours
marto answered the question on October 1, 2019 at 09:59
- The diagrams below show some physical methods of separating mixtures.(Solved)
The diagrams below show some physical methods of separating mixtures.
Name the methods of separation labeled W, X and Y
Date posted: October 1, 2019. Answers (1)
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Study the figure below and use it to answer the following questions.
a) Name the parts labeled X and Y.
b) Identify the flame.
c) Which part of the flame is the hottest?
Date posted: October 1, 2019. Answers (1)
- Candle wax is an example of a hydrocarbon.
a) What is a hydrocarbon
b)Name the two products formed when hydrocarbons burn in oxygen.(Solved)
Candle wax is an example of a hydrocarbon.
a) What is a hydrocarbon
b)Name the two products formed when hydrocarbons burn in oxygen.
Date posted: October 1, 2019. Answers (1)
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The set-up below was used to prepare a sample of oxygen gas. Study it and answer the questions that follow.
a) Write a word equation for the reaction that produces oxygen above.
b) State two physical properties of oxygen gas.
c) State two uses of oxygen.
Date posted: October 1, 2019. Answers (1)
- State whether solutions with the following pH values are acidic, basic or neutral.
pH 3 –
pH 11 –
pH 14 –
pH 7 –(Solved)
State whether solutions with the following pH values are acidic, basic or neutral.
pH 3 –
pH 11 –
pH 14 –
pH 7 –
Date posted: October 1, 2019. Answers (1)
- Study the diagram below for the reaction between sodium carbonate and hydrochloric acid and answer the questions that follow(Solved)
Study the diagram below for the reaction between sodium carbonate and hydrochloric acid and answer the questions that follow.
a) Explain what was observed in:
i) Test tube A.
ii) Test tube B.
b) Write a word equation for the reaction which took place in test tube.
Date posted: October 1, 2019. Answers (1)
- Write word equations for the following reactions.(Solved)
Write word equations for the following reactions.
i) Zinc and hydrochloric acid.
ii) Potassium hydroxide and sulphuric (VI) acid.
iii) Magnesium carbonate and nitric (V) acid.
Date posted: October 1, 2019. Answers (1)
- Complete the following.(Solved)
Complete the following
i) Acid + metal →
ii) Acid + Base →
iii) Acid + Carbonate →
Date posted: October 1, 2019. Answers (1)
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i) Atom.
ii) Compound.
iii) Element(Solved)
Define:
i) Atom.
ii) Compound.
iii) Element
Date posted: October 1, 2019. Answers (1)
- Write the names of the elements represented by symbols.(Solved)
Write the names of the elements represented by symbols.
i) K –
ii) Cl –
iii) Fe –
iv) Mg –
v) C –
vi) Be-
Date posted: October 1, 2019. Answers (1)
- Distinguish between temporary physical and permanent chemical changes.(Solved)
Distinguish between temporary physical and permanent chemical changes.
Date posted: October 1, 2019. Answers (1)
- The graph below shows the shape of the curve obtained by a student when solid X was heated to boiling.(Solved)
The graph below shows the shape of the curve obtained by a student when solid X was heated to boiling.
a) Determine the melting point of solid X.
b) After the experiment the student concluded that substance x was pure substance. Explain why he concluded so.
c) If candle wax was used in the above experiment the portion QR would be horizontal. What does this tell us about candle wax?
Date posted: October 1, 2019. Answers (1)
- Identify the elements present in the following compounds.
i) Magnesium oxide.
ii) Zinc chloride
iii) Sodium sulphate.
iv) Aluminium nitrate(Solved)
Identify the elements present in the following compounds.
i) Magnesium oxide.
ii) Zinc chloride
iii) Sodium sulphate.
iv) Aluminium nitrate
Date posted: October 1, 2019. Answers (1)
- Study the diagram below and answer the question that follows.(Solved)
Study the diagram below and answer the question that follows.
a) Name the process labeled a, b, c and d.
b) Draw a similar diagram to show the effect of temperature on solid carbon (IV) oxide (dry ice)
Date posted: October 1, 2019. Answers (1)
- State two ways of preventing drug abuse.(Solved)
State two ways of preventing drug abuse.
Date posted: October 1, 2019. Answers (1)
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Explain why molten calcium chloride conducts electricity while silicon (IV) oxide does not.
Date posted: October 1, 2019. Answers (1)
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(i) Atom
(ii) Mass number(Solved)
What is meant by the terms:
(i) Atom
(ii) Mass number
(b) The formula of element T is TCl3. What is the formula of its sulphate?
Date posted: October 1, 2019. Answers (1)
- 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)
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(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)