Get premium membership and access questions with answers, video lessons as well as revision papers.
- When heated in a current of nitrogen gas, magnesium reacts to form a compound.(Solved)
When heated in a current of nitrogen gas, magnesium reacts to form a compound.
(a) Write the chemical equation of the compound formed.
(b) Calculate the volume of nitrogen at s.t.p required to react with 0.72 g of magnesium.
(Mg = 24, molar gas volume at s.t.p = 22.4 dm3)
Date posted: August 14, 2019. Answers (1)
- An element P contains two isotopes
whose relative abundance is in the ratio 9:1. Find the relative atomic mass of P.(Solved)
An element P contains two isotopes whose relative abundance is in the ratio 9:1. Find the relative atomic mass of P.
Date posted: August 14, 2019. Answers (1)
- Study the equation below and answer the question that follows.(Solved)
Study the equation below and answer the question that follows.
Identify the acid in the forward reaction. Give a reason for your answer.
Date posted: August 14, 2019. Answers (1)
- A 10 cm3 volume concentrated hydrochloric acid of density 1.18 g/cm3 and purity of 36 percent dissolved in 250 cm3 of distilled water. Calculate the...(Solved)
A 10 cm3 volume concentrated hydrochloric acid of density 1.18 g/cm3 and purity of 36 percent dissolved in 250 cm3 of distilled water. Calculate the morality of the solution. (H = 1, Cl = 35.5)
Date posted: August 14, 2019. Answers (1)
- Archeologists can determine the age of organic matter by measuring the proportion of carbon-14 present in a sample. Assuming that carbon-14 has a half- life...(Solved)
Archeologists can determine the age of organic matter by measuring the proportion of carbon-14 present in a sample. Assuming that carbon-14 has a half- life of 5600 years, calculate the age of a piece of wood found to contain 
as much carbon-14 as in a living material.
Date posted: August 14, 2019. Answers (1)
- Explain the observation made in the experiment whose set up is shown below.(Solved)
Explain the observation made in the experiment whose set up is shown below.
Date posted: August 14, 2019. Answers (1)
- Element G and T have atomic number 20 and 9, respectively.(Solved)
Element G and T have atomic number 20 and 9, respectively.
(a) Write down the electron arrangement of the ion of G.
(b) Which element has the same electron arrangement as the ion of T?
(c) Write the formula of compound formed by reaction of G and T.
Date posted: August 14, 2019. Answers (1)
- An Element X has first, second and third ionization energies. State and explain how their trends compare.(Solved)
An Element X has first, second and third ionization energies. State and explain how their trends compare.
Date posted: August 5, 2019. Answers (1)
- Why is an atom said to be electrically neutral?(Solved)
Why is an atom said to be electrically neutral?
Date posted: August 5, 2019. Answers (1)
- Name one ore of Zinc metal(Solved)
Name one ore of Zinc metal
Date posted: August 5, 2019. Answers (1)
- A sample of a colorless solution is suspected to be Zinc (II) sulphate. Describe some tests that can be carried to prove this.(Solved)
A sample of a colorless solution is suspected to be Zinc (II) sulphate. Describe some tests that can be carried to prove this.
Date posted: August 5, 2019. Answers (1)
- Calculate the percentage of nitrogen in calcium nitrate(Solved)
Calculate the percentage of nitrogen in calcium nitrate
Date posted: August 5, 2019. Answers (1)
- Dry carbon (II) oxide gas reacts with hot lead (II) oxide as shown in the equation below.(Solved)
Dry carbon (II) oxide gas reacts with hot lead (II) oxide as shown in the equation below.
a) Name another gas that can be used to function as carbon (II) oxide in this experiment.
b) With an appropriate reason, identify the oxidizing agent in the equation above.
Date posted: August 5, 2019. Answers (1)
- Highlight one precaution observed in each of the following cases:
i. When evaporating Ethanol.
ii. When heating to dryness a hydrated salts.(Solved)
Highlight one precaution observed in each of the following cases:
i. When evaporating Ethanol.
ii. When heating to dryness a hydrated salts.
Date posted: August 5, 2019. Answers (1)
- A metal Y with atomic number 11 burns in chlorine to produce a white solid X.Describe the following properties of X in terms of
i)...(Solved)
A metal Y with atomic number 11 burns in chlorine to produce a white solid X.Describe the following properties of X in terms of
i) Solubility.
ii).Electrical conductivity
Date posted: August 5, 2019. Answers (1)
- Excess chlorine was bubbled through a solution of potassium bromide. State and explain the observation made.(Solved)
Excess chlorine was bubbled through a solution of potassium bromide. State and explain the observation made.
Date posted: August 5, 2019. Answers (1)
- Why is cryolite added to the pure Aluminium oxide in the process of extracting the metal?.(Solved)
Why is cryolite added to the pure Aluminium oxide in the process of extracting the metal?.
Date posted: August 5, 2019. Answers (1)
- The table below gives some information about four elements. The letters are not their actual symbols.(Solved)
The table below gives some information about four elements. The letters are not their actual symbols.
i. Write the electron arrangement of any element in same chemical family as element L.
ii. Compare the reactivity of elements K and N.
iii. Account for the difference in ionic and atomic radii of element M.
Date posted: August 5, 2019. Answers (1)
- Give two reasons why spoons are electroplated.(Solved)
Give two reasons why spoons are electroplated.
Date posted: August 5, 2019. Answers (1)
- An indicator established the following equilibrium when dissolved in water.(Solved)
An indicator established the following equilibrium when dissolved in water.
State and explain the observation made when Lime water is added?
Date posted: August 5, 2019. Answers (1)