1. (a ) Define the term compound.
(b) State two conditions necessary for the cracking of petroleum fractions.
(c) Name two transition elements that are used as catalyst.
(d) (i) Write an equation for the reaction between zinc dust and trioxonitrate (V) solution.
(ii) Which of the reactants in 1(d)(i) is:
I. reduced;
II. oxidized.
(e) Two isotopes of oxygen \(16O\) and \(18O\) have relative abundance of 90 % and 10 % respectively. Calculate the relative atomic mass of oxygen.
(f) List two ores of iron.
(g) (i) What is biotechnology?
(ii) Name one product that can be obtained using biotechnology.
(h) Define the term element.
(i) State two sources of methane in the atmosphere.
(j) Explain briefly why the trend of the boiling points for group VII elements is in the order \(I_2 > Brl_2 > Cl_2\).
(a) A compound is a pure substance formed when two or more elements combine chemically in a fixed proportion by mass.
(b) A high temperature and the presence of a catalyst (e.g. silica-alumina/zeolite). (High pressure is used in thermal cracking.)
(c) Iron and vanadium (also platinum or nickel).
(d)(i) (Taking the salt as silver trioxonitrate(V), AgNO3.)
\[ \text{Zn} + 2\text{AgNO}_3 \to \text{Zn(NO}_3)_2 + 2\text{Ag} \]
(d)(ii) I. Reduced: the silver ion, Ag+ (gains electrons). II. Oxidized: zinc (loses electrons).
(e) Relative atomic mass of oxygen
\[ A_r = \frac{(16 \times 90) + (18 \times 10)}{100} = \frac{1440 + 180}{100} = \frac{1620}{100} = 16.2 \]
(f) Haematite (Fe2O3) and magnetite (Fe3O4).
(g)(i) Biotechnology is the use of living organisms (or their enzymes/systems) to make or modify products useful to man.
(g)(ii) Ethanol (or antibiotics, insulin, yoghurt).
(h) An element is a substance made of only one kind of atom that cannot be split into simpler substances by ordinary chemical means.
(i) Decomposition of organic matter in swamps/marshes (biogas) and the digestion of food by ruminant animals (also natural gas and rice paddies).
(j) Boiling point increases in the order Cl2 < Br2 < I2 because, down the group, the molecular size and number of electrons increase, so the van der Waals (dispersion) forces between molecules become stronger and more energy is needed to separate them.
(a) A compound is a pure substance formed when two or more elements combine chemically in a fixed proportion by mass.
(b) A high temperature and the presence of a catalyst (e.g. silica-alumina/zeolite). (High pressure is used in thermal cracking.)
(c) Iron and vanadium (also platinum or nickel).
(d)(i) (Taking the salt as silver trioxonitrate(V), AgNO3.)
\[ \text{Zn} + 2\text{AgNO}_3 \to \text{Zn(NO}_3)_2 + 2\text{Ag} \]
(d)(ii) I. Reduced: the silver ion, Ag+ (gains electrons). II. Oxidized: zinc (loses electrons).
(e) Relative atomic mass of oxygen
\[ A_r = \frac{(16 \times 90) + (18 \times 10)}{100} = \frac{1440 + 180}{100} = \frac{1620}{100} = 16.2 \]
(f) Haematite (Fe2O3) and magnetite (Fe3O4).
(g)(i) Biotechnology is the use of living organisms (or their enzymes/systems) to make or modify products useful to man.
(g)(ii) Ethanol (or antibiotics, insulin, yoghurt).
(h) An element is a substance made of only one kind of atom that cannot be split into simpler substances by ordinary chemical means.
(i) Decomposition of organic matter in swamps/marshes (biogas) and the digestion of food by ruminant animals (also natural gas and rice paddies).
(j) Boiling point increases in the order Cl2 < Br2 < I2 because, down the group, the molecular size and number of electrons increase, so the van der Waals (dispersion) forces between molecules become stronger and more energy is needed to separate them.
