NECO SSCE - Chemistry - 2003

Naturally occurring lithium consists of 90% \( ^7_3Li \text{ and 10% } ^6_3 Li. \) What is the relative atomic mass of lithium?

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What is the change in the oxidation number of phosphorus in the following reaction?

4P(s) + 5O₂(ag) → 2P₂O₅(s)

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Which method is used for the purification of copper from its ore?

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The boiling point of water is higher than the boiling point of ethanol because

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Which separation technique is routinely applied in the petroleum industry?

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The reaction C₂H₆ → C₂H + H₂ is known as

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What is formed when starch is completely hydrolysed?

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What change will occur to the equilibrium mixture
\( 2CrO^{2-}_4(aq) + 2H^+(aq) ⇔ Cr_2O^{2-}_7(aq) + H_2O(l) \) when excess sodium hydrogen solution is added?

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An organic compound gave the following results on analysis: C = 29.3% ; H = 5.7%; Br = 65%.
What is the empirical formula of the compound? [C = 12, H = 1, Br=80]

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The number of hydrogen ions in 1.0dm6.00x10³ of a 0.25 mole dm6.00x10^-3 tetraoxosulphate(Vl) acid solution is
[Avogadro constant = 6.0 x 1 0]

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B is an isotope of the element \(^{238} _{92}Ur\). The isotope B has

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Which formula is used to indicate the degree of acidity of an acid?

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Which metal is extracted from bauxite?

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How many Faradays of electricity are required to liberate 9g of aluminium? [Al = 27]

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What is the number of moles of NaHCO₃in 250cm³ of its solution if the solution contains 8.4 g of NaHCO₃ in 1 dm³ of the solution. [Na = 23, 0 = 16, C = 12, H = 1)

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Which metal bromide is widely used in photography?

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A calcium atom and a calcium ion have the same

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Why does the treatment of cotton fabrics with dilute acids weaken the materials?

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What is the concentration (in mol dm³) of a solution containing 28 g of potassium hydroxide per 100 cm³ of solution? (K=39; H=1; 0=16)

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Chlorine is used in water purification because it

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Which is NOT a synthetic polymer?

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What is the IUPAC name of CH₃CCI=C(CH₃)2?

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Which compound will give propane when it Is dehy drated by an excess of hot, concentrated tetraoxosvlphate(VI) acid?

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Which element is the most electronegative?

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The pH of water is 7.

What is the pH of orange juice?

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In the reaction 2H₂S(g) + SO₂(g) → 2H₂SO(I)+3S(s)SO₂is acting as _agent

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Which hydrocarbon does NOT exhibit structural isomerism?

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Which statement is NOT true about the composition of starch?

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What mass of silver is deposited when a current of 2.6 A is passed through a solution of a silver salt for 40 minutes? [Ag= 108 ; F=96500C]

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Chlorine displaces bromine from aqueous potassium bromide because

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Small amounts of compounds of transition metals are sometimes added to glass during manufacture in order to make the glass

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An atom of element X has an electronic configuration of \( 1s^22p^33s^23p^2. \) In which group of the periodic table is X?

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Ethene decolourises acidified potassium tetraoxomanganate(VII) solution. Which gas will decolourise bromine water?

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Why is tetraoxosulphate(VI) acid NOT used for making carbon dioxide from calcium carbonate? It is

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Which metal is a constituent of both bronze and solder?

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What change will occur during the electrolysis of brine using carbon electrodes?

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At s.t.p, a mole of chlorine occupies 22.4dm³. If the temperature is changed to 35°C and the pressure to 750mHg the of the new volume will be [Cl = 35.5]

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What mass of copper is deposited when 6.5g of granulated zinc reacts with excess copper(II) tetraoxosulphate(VI) solution?

The equation for the reaction is: Zn(s) + \( CuSO_4(aq)→ ZnSO_4(aq)+ Cu(s)\)[CU= 64; Zn=65]

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