1. It is not flammable
2. It is less dense than air
johnmulu answered the question on February 2, 2017 at 08:46
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Write the formula of sulphide of an element C, whose atomic number is 5. C is not the actual symbol of the element
(Solved)
Write the formula of sulphide of an element C, whose atomic number is 5. C is not the actual symbol of the element.
Date posted:
February 2, 2017
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Answers (1)
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An element Y has the electronic configuration 2.8.5
(Solved)
An element Y has the electronic configuration 2.8.5
a) which period of the periodic table does the element belong
b) Write a formula of the most stable anion formed when element Y ionises
c) Explain the difference between the atomic radius of element Y and its ionic radius
Date posted:
February 2, 2017
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Answers (1)
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Distinguish between ionisation energy and electron affinity of an element
(Solved)
Distinguish between ionisation energy and electron affinity of an element.
Date posted:
February 2, 2017
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Answers (1)
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What name is given to an element which appears in group (II) of the periodic table?
(Solved)
What name is given to an element which appears in group (II) of the periodic table?
Date posted:
February 2, 2017
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Answers (1)
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The atomic numbers of phosphorus, sulphur and potassium are 15, 16 and 19 respectively. The formulae of their ions are P3-, S2- and K+. These ions have the same number of electrons
(Solved)
The atomic numbers of phosphorus, sulphur and potassium are 15, 16 and 19 respectively. The formulae of their ions are P3-, S2- and K+. These ions have the same number of electrons
i) Write the electron arrangement of the ions
ii) Arrange the ions in the increasing ionic radius starting with the smallest. Give a reason for the order
Date posted:
February 2, 2017
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Answers (1)
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What is meant by the terms (i) Element (ii) Atomic number
(Solved)
What is meant by the terms
i) Element
ii) Atomic number
Date posted:
February 2, 2017
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Answers (1)
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What are isotopes?
(Solved)
What are isotopes?
Date posted:
February 2, 2017
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Answers (1)
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Why is calcium more reactive than beryllium?
(Solved)
Why is calcium more reactive than beryllium?
Date posted:
February 2, 2017
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Answers (1)
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Write the electronic configuration of calcium (atomic number 20) and beryllium (atomic number 4)
(Solved)
Write the electronic configuration of calcium (atomic number 20) and beryllium (atomic number 4).
Date posted:
February 2, 2017
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Answers (1)
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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
(Solved)
With reference to atomic number of one, explain why hydrogen can be placed in either group I and VII of the periodic table.
Date posted:
February 2, 2017
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Answers (1)
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The electron arrangement of ions X3+ and Y2- are 2,8 and 2,8,8 respectively
(Solved)
The electron arrangement of ions X3+ and Y2- are 2,8 and 2,8,8 respectively
a) Write the electronic arrangement of the elements X and Y
b) Write the formula of the compound that would be formed between X and Y
Date posted:
February 2, 2017
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Answers (1)
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When a candle was burnt completely, the total mass of products was found to be greater than the original mass of the candle. Explain
(Solved)
When a candle was burnt completely, the total mass of products was found to be greater than the original mass of the candle. Explain
Date posted:
February 2, 2017
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Answers (1)
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A candle wax is mainly a compound consisting of two elements. Name the two elements
(Solved)
A candle wax is mainly a compound consisting of two elements. Name the two elements
Date posted:
February 2, 2017
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Answers (1)
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In an experiment, a piece of magnesium ribbon was cleaned with steel wool. 2.4 g of the clean magnesium ribbon was placed in a crucible and completely burnt in oxygen
(Solved)
In an experiment, a piece of magnesium ribbon was cleaned with steel wool. 2.4 g of the clean magnesium ribbon was placed in a crucible and completely burnt in oxygen. After cooling, the product weighed 4.0 g
a) Explain why it was necessary to clean the magnesium ribbon
b) What observation was made in the magnesium ribbon
c) Why was there an increase in mass
Date posted:
February 2, 2017
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Answers (1)
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When wood is burnt, a grey powder called ash remains. The ash is stirred with water and filtered a colourless solution is obtained
(Solved)
When wood is burnt, a grey powder called ash remains. The ash is stirred with water and filtered a colourless solution is obtained
a) What is the main component of the colourless solution
b) Explain your answer in (a) above
c) State the observation that would be made if methyl orange indicator was passed through the solution of ash.
Date posted:
February 2, 2017
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Answers (1)
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Name another gas which used together with oxygen in welding
(Solved)
Name another gas which used together with oxygen in welding
Date posted:
February 2, 2017
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Answers (1)
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When magnesium metal is burnt in air, it reacts with both oxygen and nitrogen gases giving a white ash
(Solved)
When magnesium metal is burnt in air, it reacts with both oxygen and nitrogen gases giving a white ash. Write two equations for the reactions that take place
Date posted:
February 2, 2017
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Answers (1)
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Explain how you would separate a mixture of nitrogen and oxygen gases given that their boiling points are
(Solved)
Explain how you would separate a mixture of nitrogen and oxygen gases given that their boiling points are - 196o C and - 183o C
Date posted:
February 2, 2017
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Answers (1)
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(a) Name a suitable solvent for extracting an indicator from flowers (b) Give a reason why the solvent named in (a) above is used
(Solved)
a) Name a suitable solvent for extracting an indicator from flowers
b) Give a reason why the solvent named in (a) above is used
Date posted:
February 2, 2017
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Answers (1)
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Describe how pH of anti-acid (Actal) powder can be determined in the laboratory
(Solved)
Describe how pH of anti-acid (Actal) powder can be determined in the laboratory
Date posted:
February 2, 2017
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Answers (1)