2003 NECO Chemistry Past Questions

Questions

1. 1.

   The number of hydrogen ions in 1.0dm$^3$ of a 0.25 mole tetraoxosulphate(Vl) acid solution is [Avogadro constant = 6.02 x 10$^{23}$]

   1. A.1.45x1023
   2. B.1.50 x l023
   3. C.3.00x1023
   4. D.3.15x1023
   5. E.6.00x1023

   Show answer

   Answer: C. 3.00x1023

   Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

2. 2.

   Which hydrocarbon does NOT exhibit structural isomerism?

   1. A.C3H6
   2. B.C4H6
   3. C.C4H8
   4. D.C4H10
   5. E.C5H12

   Show answer

   Answer: A. C3H6

   Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

3. 3.

   Which metal bromide is widely used in photography?

   1. A.calcium bromide
   2. B.magnesium bromide
   3. C.potassium bromide
   4. D.silver bromide
   5. E.sodium bromide

   Show answer

   Answer: D. silver bromide

   Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

4. 4.

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

   1. A.$[H^+] = ^{\text{mass of acid relative}} molecular mass of acid$
   2. B.F = number of H+ = ions x molar mass of the acid
   3. C.Kw = [H+][OH-]
   4. D.pH = - log10[H+]
   5. E.pKa = -log10Ka

   Show answer

   Answer: D. pH = - log10[H+]

   Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

5. 5.

   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]

   1. A.6.89g
   2. B.6.93g
   3. C.6.98g
   4. D.7.04g
   5. E.7.12g

   Show answer

   Answer: C. 6.98g

   Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

6. 6.

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

   1. A.distillation
   2. B.electrochemical
   3. C.electrolysis
   4. D.neutralization
   5. E.reduction

   Show answer

   Answer: C. electrolysis

   Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

7. 7.

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

   1. A.2-chloro -3 methylbut -2yne
   2. B.2 -chloro -3 methylbut -2ene
   3. C.2 -chloro -3 methylbutene
   4. D.3- methyl -2-chlorobut -2-ene
   5. E.3- methyl -2. chlorobut -2 yne

   Show answer

   Answer: B. 2 -chloro -3 methylbut -2ene

   Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

8. 8.

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

   1. A.a dehydrating agent
   2. B.a strong acid
   3. C.an oxidising agent
   4. D.dibasic
   5. E.forms insoluble calcium tetraoxosulphate(Vl)

   Show answer

   Answer: E. forms insoluble calcium tetraoxosulphate(Vl)

   Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

9. 9.

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

   1. A.46 protons and 119 neutrons
   2. B.92 protons and 92 neutrons
   3. C.92 protons and 146 neutrons
   4. D.92 protons and 238 neutrons

   Show answer

   Answer: C. 92 protons and 146 neutrons

   Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

10. 10.

    The reaction C2H6 → C2H + H2 is known as

    1. A.dehydration
    2. B.dehydrogenation
    3. C.displacement
    4. D.hydrogenation
    5. E.reduction

    Show answer

    Answer: B. dehydrogenation

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

11. 11.

    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?

    1. A.A yellow precipitate of Cr(OH)3 is formed
    2. B.An orange precipitate of Cr(OH)3 is formed
    3. C.The colour changes from orange to yellow
    4. D.The colour changes from yellow to orange
    5. E.There is no visible reaction.

    Show answer

    Answer: C. The colour changes from orange to yellow

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

12. 12.

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

    1. A.CH4
    2. B.C2H6
    3. C.C3H6
    4. D.C3H8
    5. E.C6H6

    Show answer

    Answer: C. C3H6

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

13. 13.

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

    1. A.the bonding in water is electrovalent (ionic) whereas the bonding in ethanol is convalent
    2. B.the hydrogen bonding between water molecules is stronger than the hydrogen bonding between ethanol molecules
    3. C.water has a higher lattice energy than ethanol.
    4. D.water has hydrogen bonding between its molecules but ethanol has no hydrogen bonging between its molecules;
    5. E.water is a better solvent than ethanol.

    Show answer

    Answer: B. the hydrogen bonding between water molecules is stronger than the hydrogen bonding between ethanol molecules

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

14. 14.

    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)

    1. A.1
    2. B.0.25
    3. C.0.05
    4. D.0.025
    5. E.0.01

    Show answer

    Answer: D. 0.025

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

15. 15.

    What is the concentration (mol dm$^{-3}$) of a solution containing 28 g of potassium hydroxide per 100 cm$^3$ of solution? (K=39; H=1; O=16)

    1. A.0.01
    2. B.0.05
    3. C.1.0
    4. D.5.0
    5. E.2.8

    Show answer

    Answer: D. 5.0

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

16. 16.

    What is the change in the oxidation number of phosphorus in the following reaction? 4P(s) + 5O2(ag) → 2P2O5(s)

    1. A.0 to 2
    2. B.0 to 5
    3. C.4 to 2
    4. D.4 to 5
    5. E.4 to 10

    Show answer

    Answer: B. 0 to 5

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

17. 17.

    A calcium atom and a calcium ion have the same

    1. A.chemical properties
    2. B.electric charge
    3. C.electronic structure
    4. D.number of electrons
    5. E.number of neutrons

    Show answer

    Answer: E. number of neutrons

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

18. 18.

    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]

    1. A.3.2 g
    2. B.3.25 g
    3. C.6.4 g
    4. D.6.5 g
    5. E.64.0 g

    Show answer

    Answer: C. 6.4 g

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

19. 19.

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

    1. A.a bleaching
    2. B.a dehydrating
    3. C.an oxidizing
    4. D.a precipitating
    5. E.a reducing

    Show answer

    Answer: C. an oxidizing

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

20. 20.

    Which metal is extracted from bauxite?

    1. A.aluminium
    2. B.calcium
    3. C.copper
    4. D.magnesium
    5. E.tin

    Show answer

    Answer: A. aluminium

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

21. 21.

    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]

    1. A.$\frac{760\times 22.4\times 308}{750\times 273\times 35.5} dm^3$
    2. B.$\frac{760\times 22.4\times 308}{750\times 273}dm^3$
    3. C.$\frac{750\times 22.4\times 35.5}{760\times 273}dm^3$
    4. D.$\frac{760\times 22.4\times 35.5}{750\times 22.3\times 273}dm^3$
    5. E.$\frac{760\times 22.4\times 35.5}{750\times 308}dm^3$

    Show answer

    Answer: B. $\frac{760\times 22.4\times 308}{750\times 273}dm^3$

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

22. 22.

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

    1. A.Cotton is hydrolysed completely to glucose
    2. B.The fabrics are soluble in dilute acids
    3. C.The molecular chains are partially broken
    4. D.The molecular chain length f the fabric increases
    5. E.The thread holding the fabric together Is completely destroyed.

    Show answer

    Answer: C. The molecular chains are partially broken

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

23. 23.

    Which element is the most electronegative?

    1. A.calcium
    2. B.fluorine
    3. C.iodine
    4. D.oxygen
    5. E.sodium

    Show answer

    Answer: B. fluorine

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

24. 24.

    Which separation technique is routinely applied in the petroleum industry?

    1. A.chromatography
    2. B.distillation
    3. C.evaporation
    4. D.fractional crystallization
    5. E.fractional distillation

    Show answer

    Answer: E. fractional distillation

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

25. 25.

    Which is NOT a synthetic polymer?

    1. A.nylon
    2. B.Orion
    3. C.Perspex
    4. D.polystyrene
    5. E.wool

    Show answer

    Answer: E. wool

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

26. 26.

    An atom of element X has an electronic configuration of $1s^22S^22p^63s^23p^3.$ In which group of the periodic table is X?

    1. A.$\text{0}$
    2. B.2
    3. C.3
    4. D.4
    5. E.5

    Show answer

    Answer: E. 5

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

27. 27.

    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]

    1. A.CH3Br
    2. B.C2H5Br
    3. C.C3H5Br
    4. D.C3H7Br
    5. E.C4H9Br

    Show answer

    Answer: D. C3H7Br

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

28. 28.

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

    1. A.Chlorine will be given off at the anode
    2. B.Oxygen gas will be given off at the anode
    3. C.Sodium will be deposited at the cathode
    4. D.The resulting solution, after electrolysis, will be acidic.
    5. E.The volumes of hydrogen and chlorine given off during the same time are equal

    Show answer

    Answer: A. Chlorine will be given off at the anode

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

29. 29.

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

    1. A.0.1
    2. B.0.3
    3. C.1
    4. D.2.7
    5. E.3

    Show answer

    Answer: C. 1

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

30. 30.

    Chlorine displaces bromine from aqueous potassium bromide because

    1. A.bromine is a liquid at room temperature
    2. B.bromine is weakly acidic.
    3. C.bromine has a greater atomic radius than chlorine
    4. D.chlorine is a stronger oxidising agent than bromine.
    5. E.the density of chlorine is less than the density of bromine.

    Show answer

    Answer: D. chlorine is a stronger oxidising agent than bromine.

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

31. 31.

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

    1. A.6
    2. B.6.8
    3. C.6.9
    4. D.7
    5. E.7.1

    Show answer

    Answer: C. 6.9

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

32. 32.

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

    1. A.CH3CH2CHO
    2. B.CH3CH2CH2OH
    3. C.CH3CH2COQH
    4. D.CH3CH20CH
    5. E.CH3CH3OH

    Show answer

    Answer: B. CH3CH2CH2OH

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

33. 33.

    What is formed when starch is completely hydrolysed?

    1. A.fructose
    2. B.glucose
    3. C.lactose
    4. D.maltose
    5. E.sucrose

    Show answer

    Answer: B. glucose

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

34. 34.

    Chlorine is used in water purification because it

    1. A.bleaches impurities in the water
    2. B.decolorizes water
    3. C.destroys bacteria
    4. D.is extremely soluble in water
    5. E.is pleasant tasting

    Show answer

    Answer: C. destroys bacteria

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

35. 35.

    The pH of water is 7. What is the pH of orange juice?

    1. A.7
    2. B.above 10
    3. C.below 2
    4. D.between 5.5 and 6.5
    5. E.between 7.5 and 8.5

    Show answer

    Answer: D. between 5.5 and 6.5

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

36. 36.

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

    1. A.acquire certain colours
    2. B.easier to melt
    3. C.easier to mould
    4. D.little brittle
    5. E.more transparent

    Show answer

    Answer: A. acquire certain colours

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

37. 37.

    Which metal is a constituent of both bronze and solder?

    1. A.copper
    2. B.lead
    3. C.silver
    4. D.tin
    5. E.zinc

    Show answer

    Answer: D. tin

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app

38. 38.

    Which statement is NOT true about the composition of starch?

    1. A.It contains only the atoms of carbon, hydrogen oxygen
    2. B.It is a polysaccharide
    3. C.Its empirical formula is C2H20.
    4. D.It is made from the monomerC6H12O6.
    5. E.The hydrogen and oxygen atoms are in the ratio 2:1.

    Show answer

    Answer: C. Its empirical formula is C2H20.

    Get a step-by-step AI explanation in the appGet a step-by-step AI explanation in the app