Recent questions without an upvoted answer

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One of the ores of iron is haematite, Fe2O3. Give the name and formula of two other ores of iron.

asked Jun 21, 2021 in Chemistry Form 4 by anonymous

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Some compounds such as CFCs and DDT are regarded as environmental pollutants. Give the complete names of

asked Jun 21, 2021 in Chemistry Form 3 by anony mous

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A factory uses 100 kg of ammonia each day to produce 160 kg of nitrogen(II) oxide. Calculate the percentage yield of nitrogen(II) oxide.

asked Jun 21, 2021 in Chemistry Form 3 by anonymous

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Methane reacts with bromine as shown in the following equation. CH4(g) + Br2(g) → CH3Br(g) + HBr(g) Using the bond energies in the Table, calculate the enthalpy change, ΔH for the reaction.

asked Jun 21, 2021 in Chemistry Form 4 by anony mous

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One of the reactions in the manufacture of nitric(V) acid involves catalytic oxidation of ammonia as shown in the equation.

asked Jun 21, 2021 in Chemistry Form 4 by anonymous

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Dichromate(VI) ions are orange in colour while chromate(VI) ions are yellow. Consider the following equilibrium.

asked Jun 21, 2021 in Chemistry Form 4 by anonymous

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State what is meant by the term 'dynamic equilibrium.

asked Jun 21, 2021 in Chemistry Form 1 by anonymous

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peroxide decomposition Sodium carbonate is prepared on large scale by the Solvay process. The equation for the main reaction that takes place in the carbonator is: NaCl(aq) + NH3(g) + CO2(g)+ H2O(l) → NH4Cl(aq) + NaHCO3(s)

asked Jun 21, 2021 in Chemistry Form 2 by anony mous

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In the laboratory, methane can be prepared from salts of alkanoic acids. Describe how methane is prepared from sodium ethanoate.

asked Jun 21, 2021 in Chemistry Form 3 by anonymous

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The main component in natural gas is methane. Describe how methane in natural gas is formed.

asked Jun 21, 2021 in Chemistry Form 3 by anonymous

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Incomplete combustion of pentane may result in air pollution. Write an equation to illustrate this combustion.

asked Jun 21, 2021 in Chemistry Form 3 by anonymous

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The Figure shows an energy level diagram for the decomposition of hydrogen peroxide using a catalyst

asked Jun 21, 2021 in Chemistry Form 4 by anony mous

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Draw and name two isomers of pentane

asked Jun 21, 2021 in Chemistry Form 3 by anonymous

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Crude oil is a mixture of hydrocarbons which are separated by fractional distillation. One of the components obtained contains an alkane A, with eleven carbon atoms.

asked Jun 21, 2021 in Chemistry Form 3 by anonymous

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Nitrogen(IV) oxide is prepared by heating lead(ll) nitrate.

asked Jun 21, 2021 in Chemistry Form 3 by anony mous

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Study the information in the table and answer the questions that follow. The elements belong to the same chemical family. (The letters are not actual symbols of the elements)

asked Jun 21, 2021 in Chemistry Form 2 by anony mous

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A metallic box weighs 188N and measures 10cm by 30 cm by 8 cm. Determine the maximum pressure it can exert when lying on one of its surfaces.

asked Jun 21, 2021 in Physics Form 1 by anonymous

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Excess dilute hydrochloric acid was added to an alloy of copper and zinc in a beaker.

asked Jun 21, 2021 in Chemistry Form 4 by anony mous

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When chlorine is bubbled through hot concentrated sodium hydroxide solution, sodium chlorate(V), sodium chloride and water are formed.

asked Jun 21, 2021 in Chemistry Form 2 by anony mous

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A step down transformer has 600 turns in the primary coil. The input voltage is 120 V while the output voltage is 24 V. Determine the number of turns in the secondary coil.

asked Jun 21, 2021 in Physics Form 4 by anonymous

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