QUESTIONS
Answer all the questions in the spaces provided.
- The diagram below shows how muddy water can be made clean. Study it and answer the
questions that follow.- Name the apparatus labeled X. (1 mk)
- Give a reason why the clean water took a long time to drop into the boiling tube.(2 mks).
- In the experiment to study the effect of heat on naphthalene the following set up was used.
- Name the apparatus labeled A and B. (2 mks)
A -
B – - The curve shown below was obtained when solid naphthalene was heated to boiling.
- Explain in molecular terms the changes occurring in portions :- (2 mks)
AB –
DE - - What is the significance of portion BC? (1 mk)
- Explain in molecular terms the changes occurring in portions :- (2 mks)
- Name the apparatus labeled A and B. (2 mks)
- In the process of separating or extracting oil from castor oil seeds in the laboratory, students from Anestar schools crushed the seed sand then added propanone (acetone) instead of water.
- Why were the seeds first crushed? (1 mk)
- Explain how the oil can be separated from propanone. (2 mks)
- Name the method of separation that can most suitably be used to separate the following mixtures.
- Gasoline from petroleum - (1 mks)
- Benzoic acid from potassium carbonate - (1 mk)
- Oil from Cashew nuts - (1 mk)
-
- What is the role of the following parts during fractional distillation of a mixture of water and ethanol.
- Fractionating column - (1 mk)
- Glass beads in the fractionating column (1 mk)
- State any one application of the fractional distillation process. (2 mks)
- What is the role of the following parts during fractional distillation of a mixture of water and ethanol.
- The figure below shows a section of the periodic table. The letters do not represent the actual symbols of the elements.
- Give the name of the family of the elements to which M belongs. (1 mk)
- Write down the electronic configuration of the stable ion of elements. (2 mks)
- L –
- P
- Give one use of elements. (2 mks)
- What is the structure of element J. (1 mk)
- With explanation, compare the atomic radius of O and P. (2 mks)
- What is the family name given to the group number to which element E belongs to? (1 mk)
- With reasons, compare the atomic radius of elements B and A. (2 mks)
- State two industrial use of element B. (2 mks)
- With reason compare the reactivity of E and A. (3 mks)
- Write down the formula of the compound formed when D and A react. (1 mk)
- What type of bond is formed when element E reacts with oxygen? Give a reason for your answer. (2 mks)
- Which is the most reactive non-metal? Explain. (2 mks)
-
- What is an isotope? (1 mk)
- An element Q consists of 3 isotopes of mass 28, 29 and 30 and percentage abundance of 92.2%, 4.7% and 3.1% respectively. Determine the relative atomic mass of the element. (3 mks)
- Study the table below and answer the questions that follow. The letters do not represent the actual symbols of the elements.
Formula of Ion Electronic configuration. E2+ 2 D- 2.8 C+ 2.8.8 B3+ 2.8 A2+ 2.8 - Select the elements found in:-
- The same group - (1 mk)
- Period three - (1 mk)
- Select the elements found in:-
- Complete the following equations and balance them off. (2 mks)
- K + O2 →
- Ca + O2 →
- Na + O2 →
- Na(s) + HCl(aq) →
- Mg + O2 →
- Mg + H2SO4 →
- Ca + HNO3 →
- HCl + NaOH →
- Ca + H2O →
- Al + O2 →
- Using dots and crosses to represent electrons, draw the structures of the following. (4 mks)
- H2
- Cl2
MARKING SCHEME
Answer all the questions in the spaces provided.
- The diagram below shows how muddy water can be made clean. Study it and answer the
questions that follow.- Name the apparatus labeled X. (1 mk)
filter funnel - Give a reason why the clean water took a long time to drop into the boiling tube.(2 mks).
the air trapped inside prevented water going through those tubes. no space is provided for air to exit - Name the method of separation shown above
filtration
- Name the apparatus labeled X. (1 mk)
- In the experiment to study the effect of heat on naphthalene the following set up was used.
- Name the apparatus labeled A and B. (2 mks)
A - thermometer
B – beaker - The curve shown below was obtained when solid naphthalene was heated to boiling.
- Explain in molecular terms the changes occurring in portions :- (2 mks)
AB – temperature increases steadily as napthalene absorbs heat energy. This increases the kinetic energy of the particles making them vibrate more vigorously
DE - energy is used to overcome intramolecular forces holding the liquid particles together. boiling occurs. - What is the significance of portion BC? (1 mk)
melting point of wax
- Explain in molecular terms the changes occurring in portions :- (2 mks)
- Name the apparatus labeled A and B. (2 mks)
- In the process of separating or extracting oil from castor oil seeds in the laboratory, students from Anestar schools crushed the seed sand then added propanone (acetone) instead of water.
- Why were the seeds first crushed? (1 mk)
to increase the surface area of concentrate with propane (solvent) - Explain how the oil can be separated from propanone. (2 mks)
evaporation because propane being more volatile than oil, will evaporate first leaving the oil.
- Why were the seeds first crushed? (1 mk)
- Name the method of separation that can most suitably be used to separate the following mixtures.
- Gasoline from petroleum - (1 mks)
fractional distillation - Benzoic acid from potassium carbonate - (1 mk)
sublimation - Oil from Cashew nuts - (1 mk)
solvent extraction
- Gasoline from petroleum - (1 mks)
-
- What is the role of the following parts during fractional distillation of a mixture of water and ethanol.
- Fractionating column - (1 mk)
allows vapour of liquid whose boiling point has been reached to flow back to the flask - Glass beads in the fractionating column (1 mk)
increases surface area for condensation
- Fractionating column - (1 mk)
- State any one application of the fractional distillation process. (2 mks)
- distillation of crude oil to obtain fractions distillation
- distillation of liquid air to obtain nitrogen oxygen and argon
- What is the role of the following parts during fractional distillation of a mixture of water and ethanol.
- The figure below shows a section of the periodic table. The letters do not represent the actual symbols of the elements.
- Give the name of the family of the elements to which M belongs. (1 mk)
halogens - Write down the electronic configuration of the stable ion of elements. (2 mks)
- L – 2.8.8
- P - 2.8.8
- Give one use of elements. (2 mks)
A - weather baloons, hydrogenation, rocket fuel, welding
M - bleaching agent, manufacture of ammonia - What is the structure of element J. (1 mk)
giant atomic structure - With explanation, compare the atomic radius of O and P. (2 mks)
G has a lager atomic radius than H because H has many protons, leads to high nuclear change resulting to strong nuclear pull of attracting other electrons closer to their nuclear - What is the family name given to the group number to which element E belongs to? (1 mk)
alkaline (earth metals) - With reasons, compare the atomic radius of elements B and A. (2 mks)
B is smaller than A or A is larger than B or B has higher nuclear charge than A which pulls electrons closer to the nucleus - State two industrial use of element B. (2 mks)
- aeroplane on vehicle body constrtuction
- making wires for overhead cables for transmission - With reason compare the reactivity of E and A. (3 mks)
- A is more reactive than E or E is less reactive than A
- A loses outer electrons readily than E because the outer electrons of A are closely attracted since they are further from the attraction force of the nucleus - Write down the formula of the compound formed when D and A react. (1 mk)
AD2 and not D2A - What type of bond is formed when element E reacts with oxygen? Give a reason for your answer. (2 mks)
ionic or electrovalent bond
E is a metal and loses outer electrons to o xygen - Which is the most reactive non-metal? Explain. (2 mks)
O - it loses electrons readily since it has the longest atomic radius
- Give the name of the family of the elements to which M belongs. (1 mk)
-
- What is an isotope? (1 mk)
- is one of the atoms of the same element having a different mass number from the rest, but same atomic number with others of the same element - An element Q consists of 3 isotopes of mass 28, 29 and 30 and percentage abundance of 92.2%, 4.7% and 3.1% respectively. Determine the relative atomic mass of the element. (3 mks)
(92.2 × 28 + 4.7 × 29 + 3.1 × 30)
100 100 100
= 28.11
- What is an isotope? (1 mk)
- Study the table below and answer the questions that follow. The letters do not represent the actual symbols of the elements.
Formula of Ion Electronic configuration. E2+ 2 D- 2.8 C+ 2.8.8 B3+ 2.8 A2+ 2.8 - Select the elements found in:-
- The same group - (1 mk)
E and A - Period three - (1 mk)
C, B and A
- The same group - (1 mk)
- Select the elements found in:-
- Complete the following equations and balance them off. (2 mks)
- 4K + O2 → 2K2O
- 2Ca + O2 → 2CaO
- 2Na + O2 → 2Na2O
- 2Na(s) + 2HCl(aq) → 2NaCl + H2
- 2Mg + O2 → 2MgO
- Mg + H2SO4 → MgSO4 + H2
- Ca + 2HNO3 → Ca(NO3)2 + H2
- HCl + NaOH → NaCl + H2O
- Ca + H2O → Ca(OH)2
- 4Al + 3O2 → 2Al2O3
- Using dots and crosses to represent electrons, draw the structures of the following. (4 mks)
- H2
- Cl2
- H2
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