The formula for calculating maximum number of electrons held within energy level is given by 2n^2. The electrons in the second energy level is

The process of coating iron or steel with zinc, a metal that does not rust is

Element X has atomic number 11 and mass number 23. From the given information writes i. Electronic configuration of element X ii. Number of periods of element X in the periodic table iii. State whether the element X, is metal or non-metal

1. What is atomic number? (1 mk)
2. State the number of atoms present in the formula 7HNO3 (2 mk)
3. Electronic configuration of element X (atomic number 11) (1 mk)
4. State the number of atoms present in the formula: 7HNO₃ (2 mk)
5. State the number of atoms present in the formula 20PbSO4 (2 mk)
6. Number of periods of element X in the periodic table (atomic number 11) (1 mk)
7. State the number of atoms present in the formula: 20PbSO₄ (2 mk)
8. State whether the element X (atomic number 11) is metal or non-metal (1 mk)
9. Electronic configuration of element X (atomic number 11) (1 mk)
10. State whether the element X (atomic number 11), is metal or non-metal (1 mk)

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Why treated water is the best for use in the laboratory and medical facilities?

1. A fuel gas derived from decomposing biological waste is ________________ while organic matter in living plant material is _______________. (2 mk)
2. Why treated water is the best for use in the laboratory and medical facilities? (3 mk)
3. Physical changes affect the physical properties of substances, such as _____________________ and ____________________. (2 mk)
4. The possible explanation to the question asked is _______________ while a summary of the result of experiment and statement is _________________. (2 mk)
5. Signs of chocking include difficult in _______________ and _____________. (2 mk)
6. The alkali metals in the periodic table (1 mk)
7. The properties of an elements change according to their atomic number (1 mk)
8. Alkaline Earth metals in the periodic table (1 mk)
9. Have both metallic and non-metallic characteristics (1 mk)
10. They act as a catalyst in reactions and also form colored compounds (1 mk)

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List two (2) chemical properties of water.

1. A fuel gas derived from decomposing biological waste is ________________ while organic matter in living plant material is _______________. (1 mk)
2. List four (4) negative effects of global warming. (4 mk)
3. List two (2) chemical properties of water. (2 mk)
4. Physical changes affect the physical properties of substances, such as _____________________ and ____________________. (1 mk)
5. Define non-renewable sources of energy. (2 mk)
6. List two (2) classes of fuel according to their occurrence. (2 mk)
7. In the process of filtration, the solid remained is __________________ while the liquid collected is the _______________________. (1 mk)
8. Why fossil fuels are not preferred to be used as a source of fuel? (2 mk)
9. Signs of chocking include difficult in _______________ and _______________. (1 mk)

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c. Complete the table below, the first one is given as an example. Number Common name Chemical name Formula i. Soda ash Sodium Carbonate Na CO 2 3 ii. Common salt iii. Marble

1. Why radical cannot exist on its own? (3 mk)
2. Dichromate (2 mk)
3. Complete the table below, the first one is given as an example. Number Common name Chemical name Formula i. Soda ash Sodium Carbonate Na CO 2 3 ii. Common salt iii. Marble (3 mk)
4. Soda ash (2 mk)
5. Complete the table below, the first one is given as an example. Number Name of radical formula Valency (+ or -) i. Dichromate Cr O -2 2 7 ii. Ammonium iii. Nitrate (3 mk)
6. Ammonium (2 mk)
7. Common salt (2 mk)
8. Marble (2 mk)
9. Nitrate (2 mk)

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Draw and label parts of non-luminous flame

1. Define Heat (2 mk)
2. Draw and label parts of non-luminous flame (4 mk)
3. Explain why non-luminous flame is suitable for cooking? (4 mk)
4. Define Flame (2 mk)
5. Define Luminous flame (2 mk)

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i. Define water cycle. ii. Water has high surface tension. What does this mean? iii. Why treated water is the best for use in the laboratory and medical facilities? iv. List two (2) chemical properties of water. b. Explain briefly the following terms as they are used in water cycle. i. Condensation ii. Precipitation iii. Collection

1. Define water cycle. (2 mk)
2. Water has high surface tension. What does this mean? (2 mk)
3. Why treated water is the best for use in the laboratory and medical facilities? (3 mk)
4. List two (2) chemical properties of water. (3 mk)
5. Condensation (2 mk)
6. Precipitation (2 mk)
7. Collection (2 mk)

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Air is the mixture of different gases. Below are materials that are used to test different gases in air. * Anhydrous copper (II) sulphate * Lime water * Copper turnings From the above information answer the following questions:

1. Which component of air causes anhydrous copper (II) sulphate to turn blue? (0 mk)
2. Which component of air causes anhydrous copper (II) sulphate to turn blue? (1 mk)
3. What is the aim of this experiment? (2 mk)
4. What is the aim of this experiment? (2 mk)
5. Label apparatus A, B and substance C and D. (4 mk)
6. What would you observe when carbon dioxide passed through lime water? (1 mk)
7. What would you observe when carbon dioxide passed through lime water? (0 mk)
8. Write the function of substance C in apparatus B. (2 mk)
9. Write the function of substance C in apparatus B. (1 mk)
10. Which gas causes copper turning to turn black when heated in the presence of air? (1 mk)
11. Which gas causes copper turning to turn black when heated in the presence of air? (0 mk)
12. Write balanced chemical equation when carbon dioxide reacts with lime water. (0 mk)
13. Write the substance which can be used in this experiment instead of ammonium chloride. (1 mk)
14. Write the substance which can be used in this experiment instead of ammonium chloride. (2 mk)
15. Write balanced chemical equation when carbon dioxide reacts with lime water. (2 mk)
16. Why this experiment is carried out in fume chamber? (2 mk)
17. List four (4) noble gases. (0 mk)
18. List four (4) noble gases. (5 mk)

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c. Give a brief explanation on the electron arrangement according to Neils Bohr.

1. Explain briefly on the Thomson plum pudding model of atom. (0 mk)
2. ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ ______________________________________________________________ (5 mk)
3. ___________________________________________________________ (1 mk)
4. Write three (3) properties of neutrons. (0 mk)
5. ___________________________________________________________ (1 mk)
6. Give a brief explanation on the electron arrangement according to Neils Bohr. (0 mk)
7. ___________________________________________________________ (1 mk)

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b. Water is neither acidic nor basic, it is neutral. What does this mean?

1. _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ _______________________________________________________________ (4 mk)
2. Magnesium ribbon burn in air. (4 mk)
3. With the aid of equation explain what happen when: i. Magnesium ribbon burn in air. ii. Zinc granules dissolved in dilute sulphuric acid. (0 mk)
4. Water is neither acidic nor basic, it is neutral. What does this mean? (0 mk)
5. Zinc granules dissolved in dilute sulphuric acid. (4 mk)

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Why fossil fuels are not preferred to be used as a source of fuel?

1. Why fossil fuels are not preferred to be used as a source of fuel? (5 mk)

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