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- Two samples of a similar substance from different containers were investigated. The curve below represents the variation of temperature with time when heated separately.
a) Explain...(Solved)
Two samples of a similar substance from different containers were investigated. The curve below represents the variation of temperature with time when heated separately.
a) Explain the variation in the curves.
Sample I
Sample II
b) Common salt is sprinkled on roads during winter in temperate countries.
Date posted: March 28, 2019. Answers (1)
- A compound has empirical formula C3H6O and relative formula mass of 116. Determine it’s molecular formula.(C = 12, H = 1, O = 16).(Solved)
A compound has empirical formula C3H6O and relative formula mass of 116. Determine it’s molecular formula.(C = 12, H = 1, O = 16).
Date posted: March 28, 2019. Answers (1)
- Element A and B with atomic numbers 12 and 17 respectively react together.
(a) Write the electronic configurations of each
A:
...(Solved)
Element A and B with atomic numbers 12 and 17 respectively react together.
(a) Write the electronic configurations of each
A:
B:
(b) Write the formula of the compound formed between A and B.
Date posted: March 28, 2019. Answers (1)
- Explain why it is not advisable to use potassium chloride as salt bridge in the cell shown below.(Solved)
Explain why it is not advisable to use potassium chloride as salt bridge in the cell shown below.
Date posted: March 28, 2019. Answers (1)
- Aqueous sodium sulphate was electrolysed using platinum. Name the products at each electrode.
I Cathode
IIAnode(Solved)
Aqueous sodium sulphate was electrolysed using platinum. Name the products at each electrode.
I Cathode
IIAnode
Date posted: March 28, 2019. Answers (1)
- When bromine gas reacts with aqueous sodium hydroxide an equilibrium is established as shown below.(Solved)
When bromine gas reacts with aqueous sodium hydroxide an equilibrium is established as shown below.
What observation would be made if a few drops of dilute sulphuric (VI) were added to the equilibrium mixture? Explain.
Date posted: March 28, 2019. Answers (1)
- Butane burns in air according to the equation shown below.
2C4H10(g) + 13O2(g) ----> 8CO2(g) + 10H2O(l)
What volume of butane must be burnt in oxygen to...(Solved)
Butane burns in air according to the equation shown below.
2C4H10(g) + 13O2(g) ----> 8CO2(g) + 10H2O(l)
What volume of butane must be burnt in oxygen to give 11g of CO2 at r.t.p?
(Molar gas volume at r.t.p = 24.0L; C = 120; O = 16.0; H = 1.0 )
Date posted: March 28, 2019. Answers (1)
- Study the cycle below hence answer the questions that follow.(Solved)
Study the cycle below hence answer the questions that follow.
(a) What is (change)H3?
(b) Show the relationship connecting (change)H1,(change)H2 and (change)H3
Date posted: March 28, 2019. Answers (1)
- A gas of known mass occupies 200cm3 at 250C and 101325 Pa pressure. What volume would it occupy
at -230C and 1000 Pa pressure?(Solved)
A gas of known mass occupies 200cm3 at 250C and 101325 Pa pressure. What volume would it occupy
at -230C and 1000 Pa pressure?
Date posted: March 28, 2019. Answers (1)
- In an experiment soap solution was used against 3 separate samples of water. Each sample was later boiled and soap added. Each water sample was...(Solved)
In an experiment soap solution was used against 3 separate samples of water. Each sample was later boiled and soap added.Each water sample was 1000cm³. The results are tabulated below.
(a) Which sample was likely to be soft water? Explain.
(b) State the cause of change in volume of soap used to form lather in sample III.
Date posted: March 28, 2019. Answers (1)
- The electronic configuration of element X, Y and Z are given below.
X Y ...(Solved)
The electronic configuration of element X, Y and Z are given below.
X Y Z
2.8 2.8.7 2.8.18.7
Which is the most reactive element? Explain.
Date posted: March 28, 2019. Answers (1)
- The scheme below shows some reaction of salt. Study it and answer questions that follow.(Solved)
The scheme below shows some reaction of salt. Study it and answer questions that follow.
(i) Write an equation for the reaction to show formation of gas P and solid X.
(ii) Give the name and formula of the complex ion responsible for the deep blue colour in the solution.
Date posted: March 28, 2019. Answers (1)
- Excess carbon II Oxide was passed over heated sample of an oxide of iron. The following
results were obtained. Determine the empirical formular of the iron...(Solved)
Excess carbon II Oxide was passed over heated sample of an oxide of iron. The following
results were obtained. Determine the empirical formular of the iron oxide.
Mass of empty dish = 10.98g
Mass of empty dish + oxide of iron = 13.30g
Mass of dish + residue = 12.66g
(Fe = 56; C = 12; O = 16 )
Date posted: March 28, 2019. Answers (1)
- Explain why potassium chloride conducts electricity in both the molten state and in aqueous solution whereas hydrogen chloride conducts electricity only in aqueous solution and...(Solved)
Explain why potassium chloride conducts electricity in both the molten state and in aqueous solution whereas hydrogen chloride conducts electricity only in aqueous solution and not in gaseous state.
Date posted: March 28, 2019. Answers (1)
- A certain substance has a boiling point of 16800C. It does not conduct electricity when in solid form but conducts when molten. What is the...(Solved)
A certain substance has a boiling point of 16800C. It does not conduct electricity when in solid form but conducts when molten. What is the most likely structure of the substance? Explain.
Date posted: March 28, 2019. Answers (1)
- Study the diagrams below.(Solved)
Study the diagrams below.
(a) State the observations made at I and II.
(b) Write the equation to show the reactions at II if dry sulphur (IV) oxide was used in place of dry chlorine.
Date posted: March 28, 2019. Answers (1)
- The table below shows elements W, X, Y and Z and their atomic numbers. The letters are not the actual symbols of the elements. Use...(Solved)
The table below shows elements W, X, Y and Z and their atomic numbers. The letters are not the actual symbols of the elements. Use the letters to answer the questions that follow.
(a) Select an element which forms
(i) Anions.
(ii) An insoluble carbonate
(b) Which element has the largest atomic radius
Date posted: March 28, 2019. Answers (1)
- Briefly explain the following
(a) Atomic radii of alkaline earth metals are smaller than those of the corresponding alkali metals in the same period.
(b) Melting point...(Solved)
Briefly explain the following
(a) Atomic radii of alkaline earth metals are smaller than those of the corresponding alkali metals in the same period.
(b) Melting point of halogens increase down the group.
(c) Helium is a better gas for use in weather research balloons than hydrogen.
Date posted: March 28, 2019. Answers (1)
- An element E has relative atomic mass of 69.39. Given that the element has two isotopes of atomic masses 62.35 and 70.45, calculate the relative...(Solved)
An element E has relative atomic mass of 69.39. Given that the element has two isotopes of atomic masses 62.35 and 70.45, calculate the relative abundance of each of the isotopes.
Date posted: March 28, 2019. Answers (1)
- Study the diagram below and answer the questions that follow.
(a) Identify gas Z.
(b) Write the chemical equation for the reaction which produces gas Z
(c)...(Solved)
Study the diagram below and answer the questions that follow.
(a) Identify gas Z.
(b) Write the chemical equation for the reaction which produces gas Z
(c) State why the above experiment should be carried out in a fume chamber.
Date posted: March 28, 2019. Answers (1)