What is the role of charcoal in filter elements?

Given that, the amount of heat gained by water after a complete combustion of 46 g of ethanol (C2H5OH) is 8.4 kJ, what is the energy value of ethanol in J/g?

The following sets of radicals have oxidation states of either -1 or -2 except;

Which change of state of matter is applied in the following processes? (i) Metallurgy (ii) Drying of material

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For each of the radicals given in the following table, write its chemical formula, valency and oxidation state. Radical | Formula | Valency | Oxidation state ------- | -------- | -------- | --------------- Nitrate | | | Hydrogen sulphate | | | Phosphate | | | Carbonate | | | Sulphite | | |

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Complete the following table by filling in the properties of sub-atomic particles. Sub-atomic | Symbol | Location | Charge | Relative mass particle | | | | Proton | | | | Neutron | | | | Electrons | | | |

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Consider the following molecule of a certain compound then answer the questions that follow: [Diagram of a water molecule showing one oxygen and two hydrogen atoms, with covalent bonds between them] (i) What is the name of the molecule? (ii) What the molecular formula of the compound? (iii) What type of bond holds the molecules? (iv) Give any other two compounds with the same type of bond identified in (b)(iii).

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With reason(s), explain which of these elements: (a) qualifies as a noble gas. (i) functions as a halogen. (i) (iii) serves as an alkali metal. (b) By giving reason(s), indicate elements which are: placed in the same group. (i) placed in the same period. (ii)

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What is the name given to the arrangement of the electrons around the nucleus? (ii) What is the name of the layers in which the electrons are arranged? (ii) If each layer in (a) (ii) can hold a maximum number of electrons given by the formula 2n', what does n represent? (iv) By using the formula presented in (a) (iii), calculate the number of electrons in the layers K,L , M and N. (b) A sample of bromine contains 55% of the isotope with mass number 79; and 45% of the isotope with the mass number 81. Calculate the relative atomic mass of bromine.

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An experiment was conducted to find out the relationship between solubility of potassium nitrate salt in water against temperature. The results were recorded as shown in the following table: Mass of the salt (g) 10 30 50 65 87 113 Mass of water (g) 100 100 100 100 100 100 Temperature (°C) 0 20 30 40 50 60 With reference to the experiment: (a) Provide the statement of the problem. (b) Give the hypothesis. (c) Identify. (i) the dependent variable. (ii) the independent variable. (iii) the controlled variable. (d) Make a table of the collected data. (e) Make an inference or interpretation of the data collected. (f) Make a conclusion.

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