This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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Here are the solutions to the questions: 8. A student represented an atom of element J using the diagram below. b) Write the valency of element J and the oxidation number of its ion. From the diagram, element J has an electron configuration of 2, 8, 6. To achieve a stable octet, it needs to gain 2 electrons. Valency: 2* Oxidation number of its ion: -2* 9. When the oxide of metal D is heated in the presence of metal S, the oxide is reduced. The oxide of metal S is not reduced when heated together with metal E and with metal D. The oxide of metal E is reduced by metal S and not by metal D. Arrange the three metals horizontally, in their order of decreasing reactivity. Let's deduce the reactivity order: "The oxide of metal D is heated in the presence of metal S, the oxide is reduced." This means metal S is more reactive than metal D. (S > D) "The oxide of metal S is not reduced when heated together with metal E and with metal D." This means metal S is more reactive than both metal E and metal D. (S > E and S > D) "The oxide of metal E is reduced by metal S and not by metal D." This confirms S > E. It also means metal D is not reactive enough to reduce the oxide of E, so metal E is more reactive than metal D. (E > D) Combining these, the order of decreasing reactivity is: S > E > D 10. Calculate the number of nitrogen atoms that are found in 1.4g of nitrogen gas (N = 14, L = 6.023 x 10^23) Step 1: Determine the molar mass of nitrogen gas (N_2). Nitrogen gas is diatomic, so its formula is N_2. Molar mass of N_2 = 2 × atomic mass of N Molar mass of N_2 = 2 × 14 g/mol = 28 g/mol Step 2: Calculate the number of moles of nitrogen gas. Moles of N_2 = massmolar mass Moles of N_2 = 1.4 g28 g/mol = 0.05 mol Step 3: Calculate the number of nitrogen gas molecules. Number of N_2 molecules = moles × Avogadro's constant (L) Number of N_2 molecules = 0.05 mol × 6.023 × 10^23 molecules/mol Number of N_2 molecules = 3.0115 × 10^22 molecules Step 4: Calculate the number of nitrogen atoms. Each N_2 molecule contains 2 nitrogen atoms. Number of N atoms = 2 × Number of N_2 molecules Number of N atoms = 2 × 3.0115 × 10^22 atoms Number of N atoms = 6.023 × 10^22 atoms 11. Give the name of the processes that occur when the following substances are left in open watch glasses overnight: a) Concentrated sulphuric (VI) acid Hygroscopy (or absorption of water vapor) b) Sodium carbohydrate decahydrate Assuming "Sodium carbohydrate decahydrate" is a typo and refers to Sodium carbonate decahydrate (Na_2CO_3 · 10H_2O): Efflorescence