Neco Chemistry Questions And Answers 2023

Neco Chemistry Questions And Answers 2023

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OBJECTIVES QUESTIONS.

PAPER I.

1. Which of the following is not a separation Technique.
A. Crystallization
B. Distillation
C. Evaporation
D. Hydration

2. Chlorine atom and chlorine ion have the same
A. Chemical properties
B. electron charge
C. electronic configuration
D. number of electrons
E. number of protons.

3. Calculate the current in ampere when the quantity
Of electricity used isv3000 coulombs in 5 minutes
A.1500
B. 305
C. 2995
D. 600
E. 10.

4. In the periodic table, calcium and magnesium be
Long to
A. Group 2
B. Group 3
C. Group 4
D. Period 3
E. Period 4

5. Titration can be used to determine the following
Except the
A. Concentration of a solution
B. Direct mass measurement of a substa
Stance.
C. Molar mass of acid or base
D. Number of water molecules in a hydrate
E. Percentage purity of a substance

6. Elemant in group 7 are known as
A. Actinites
B. Alkali metals
C. Halogens
D. Lantanites
E. Noble gasses.

7. In the periodic table electronegativity
A. Decreases across the period
And down the group.
B. Decreases across the period but increa
See down a group.
C. Increases across the period and down the
Group.
D. Increases across the period but decreases down
The Group.
E. Increases across the period but remain constant
Down the group.

8. The following factors cause the environmental poll
Ution except.
A. Bush burning
B. Chemical warfare
C. Industrialization
D. Over population
E. Photo synthesis

9. Which of the following metals is obtain from its ore
By heating.
A. Aluminum
B. Calcium
C. Iron
D. Lead
E. Mercury

10. What is the oxidation number of nitrogen in Al
( NO3)3.?
A. +5
B. +3
C. -1
D. -3
E. -5

11. The following are products of cride oil except
A. Bitumen
B. Diesel
C. Ethanol
D. Kerosene
E. Petrol

 

12. The quality of petrol as an engine fuel improves
With a higher amount.
A. Branched chain alkanes
B. Branched chain alkenes
C. Branched chain alkynes
D. Straight chain alkanes
E. Straight chain alkenes

13. HCOOH is an example of
A. Alcohols
B. Aldehydes
C. Carboxylic acid
D. Ethers
E. Ketones

14. Which of the following is used as an antiseptic in
Hospital operation rooms.
A. Assetylene
B. Ethers
C. Ethylene
D. Methanol
E. Phenol

15. And atom is natural when it has
A. Electrons only
B. Equal number of electrons and neutrons
C. Equal number of electrons and protons
D. Neutrons only
E. Protons only

16. Which of the following gases is used in the demon
Strationof fountain experiment
A. C2H2
B. CO
C. H2S
D. NH3
E. SO2

17. A hydro carbon with vapiur density 22 contain
36g of carbon what is its molecular formula?
(C=12, H= 1).
A. C3H4
B. C3H6
C. C3H8
D. C4H8
E. C4H10

18. The following are physical properties of oxygen
Except it
A. Does not burn but support burning
B. Is a colour less and odour less gas
C. Is non poisonous.
D. Is sparingly soluble in water
E. Is less sense with air

19. Sudan III is use to test for
A. Cellulose
B. Fats and oil
C. Gluecose
D. Protein
E. Starch.

20. Calculate the quantity of electricity in coulombs
Used when a current of 2.7ampere is passed
Through a solution of silver salt for 25 minutes 20
Seconds.
A. 87.5
B. 206
C. 1350
D. 4050
E. 4104

21. And example of amphoteric oxide is
A. Al203
B. Ca0
C. Cu0
D. Si02
E. K20

22. Soluble salt can be prepared using the following
Methods except by
A. Action of dilute acid On metals
B. Action of dilute acid an insoluble base
C. Direct combination of constituent element.
D. Neutralization reaction
E. Precipitation from solutions.

23. Which of the following occasion does not undego
Neutralization with acids?.
A. Al203
B. Pb0
C. Pb02
D. Sn02
E. Zn02

24. What type of reaction take place when propence
Is formed from propanol
A. Condensation
B. Dehydration
C. Hydration
D. Hydrolysis
E. OOxidation

25. What is the PH of a solution with H+ concentration
1×10-12 moldm-3?.
A. 6
B. 8
C. 10
D. 12
E. 14

26. The process in which water is treated with slaked lime and alum is known as
A. Chlorination
B. Coagulation
C. Filtration
D. Hydrogenation
E. Sedimentation

27. The following compounds will decompose on heating except
A. Ag2CO3
B. CaCO3
C. K2CO3
D. PbCO3
E. ZnCO3.

28. The bleaching action of chlorine in water is because of its
A. Ability to accept hhydrogen.
B. Oxidizing power
C. Reducing property
D. Strong acidic nature
E. Weak acidic nature

29. The amorphous carbon used in making shoe polish and printer’s ink is
A. Animal charcoal
B. Carbon black
C. Graphite
D. Sugar charcoal
E. Wood charcoal

30. The number of phases in a chromatographic column is
A. 1
B. 2
C. 3
D. 4
E. 5.

31. Which of the following has its constituents physically bound together
A. Air
B. Coke
C. Rust
D. Salt
E. Water

32. If 100cm³ of oxygen diffuses through a porous plug in 50 seconds
Calculate the time taken for the same volume of hydrogen to passed
Through the same porous plug.
{ O=16, H=1].
A. 10.5
B. 11.5
C. 12.5
D. 17.7
E. 32.0

33. What is the mass in grams of copper deposited at the cathode when a
Solution of copper (II),
Tetraoxosulphate (vI) is electrolysed for 40 seconds using a current of 5A?
( if =96500C, molar mass of copper =63.5 g/mol).
A. 0.001
B. 0.002
C. 0.013
D. 0.066
E. 0.096

34. Calculate the mass of grams of 4 moles of oxygen gas {0=16].
A. 32
B. 64
C. 96
D. 128
E. 160

35. The kinetic theory accounts for which of these laws ?.
A. Avogadro’s
B. Boyle’s
c. Dalton’s
D. Gay llussac’s.
E. Graham’s

36. Metallurgy is a scientific process which involves the following except.
A. EElectroplating
B. Grading of metals
C. Manufacturing of alloys
D. Manufacturing of catalyst
E. Refining of metals.

37. Calculate the relative molecular mass in g/ mol of lead (II) trioxnitrate
(V). {Pb=207, N=14,0=16].
A. 132
. B. 170
. C. 222.
D.232
E. 252

38. And explanation of scientific enquiry is called
A. Hypothesis
B. Inference
C. Law
D. Observation
E. Theory

39. The law used in calculating the pressure of a gas collected over water is
A. Boyle’s
B. Charle’s
C. Dalton’s
D. Gay-lussac’s
E. Graham’s

40. Calculate the partial pressure in Hmmg if oxygen collected over water
At standard atmospheric pressure, if the saturated vapour pressure of
Water is 30 mmHg at 32°C.
A 455
B. 698
C. 700
D. 728
E. 730

41. The general formula of caustic soda is
A. Ca(0H)2
. B. K0H
C. Mg0
D. Mg(0H)2.
E. Na0H

42. The atoms 31/15 p and 32/16 S have the same number of
A. Electrons
B. Neutrons and electrons
C. Neutrons and protons
D. Neutrons
E. Protons

43. The existence of two or more forms of the same element in the same
Physical state is known as
A. Allotropy
B. Hybridization
C. Isomerism
D. Isotopy
E. Resonance

44. The technique used in separating salts which decompose easily on heating from
A. CCentrifugation
B. Chronatography
C. Crystallization
D. Seiving
E Sublimation

45. The following are deliquescent compouds except
A. CaCl2
B. Ca0
D. K0H
E. Na0H

46. What is the percentage by mass of sodium in sodium trioxocarbonate(Iv)
Decahydrate?
{H=1,c=12,0=16,Na=23].
A. 4.2
B. 8.0
C. 16.1
D. 16.8
E. 55.9

 

47. What Is the charge of an iPhone which contains 12 protons , 14 neutrons and
10 electrons ?.
A.-4
B. -2
C. +2
D. +4
E. +5

48. Ethanol is prepared from.gluecose by the process of
A. Catalic hydration
B. Fermentation
C. Hydrolysis
D. Photosynthesis
E. Respiration

49. CyHz(g)+502(g)=3C02(g)+4H20(g) from the equation above, the hydrocarbon CyHz is
A. Butane
B. Ethane
C. Ethene
D. Propane
E. Propene

50. Concentrated tetraoxosulphate (Iv) is used as a drying agent for gasses because this
A. Concentrated
B. Corrosive
C. Deliquescent
D. Effloscent
E. Hygroscopic

51. According to Charles law, the lowest attainable temperature is
A. -37°C
B. -273°C
C. -100°C
D. 0°C
E. 100°C

52. What is the oxidation number of chlorine in KCL03 and Cl2?.
A. 0 and -1
B. 0 abd and+5
C. +1 and 0
D. +5 and 0
E. +7 and 0

53. What is the charge oxidation number if Mn in the reaction below ?
MnO4(aq)+8H+5e-= Mn ²+4H2O(I).
A. +8 to +2
B. +7 to +2
C. -4 to +2
D. -1 to +2
E. -1 to +8

54. A solution when added to AgNO3(aq), dilute HNO3, and dilute NH3(aq)
Produced a white precipitate that dissolve to give a colourless solution.
Which of the following ions is confirmed in the solution?.
A. CO3²
B. Cl-
C. N3-
D. SO4²-
E. S²-

55. How many moles of KMnO4 are in 200cm³ of 0.105 moles per dm³ of a solo.
A. 0.020
B. 0.021
C. 0.050
D. 1.000
E. 2.000

56. The following metals are extracted by electrolysis except.
A. Calcium
B. Iron
C. Magnesium
D. Potassium
E. Sodium

57. The decomposition of lead (II) nitrate gives lead (II)oxide, nitrogen (iv) oxjde
And oxygen gas. What is the coefficient of nitrogen (iv)oxide in the balanced
Equation.
A. 1
B. 2
C. 3
D. 4
E. 5.

THEORY QUESTIONS.

PAPER II.

1.

(a)I. A beaker contain a mixture of amino chloride, ink and iron fillings
Mention the appropriate separation technique for each component
ii. Give two examples of eww am each of physical and chemical change.

(b) i. Mention two chemical properties of metals.
ii. With chemical equation explain the laboratory preparation of allu
Minimum get tao is I’ll hate (vi).

(C)i. When a filter paper moistened with lead (ii) trioxonitrate (v) solution
Was dropped in to a gas jar of an unknown gas X with a rotten egg smell,
The moist filter paper turned black.
I.Name the unknown gas X
ii. Give two physical properties of the unknown gas X
iii. Write an equation for the reaction between lead (ii)trioxonitrate (v)
And name gas in (c)i.
iv. State a reason for the formation of the black colouration.

(d)i. Give one digcerences between water gas and producer gas
ii. Name the shape of the following allotropes of carbon :
I.Diamond
II.Graphite

(e).(e).Mention three uses of nitrogen

2.

(a)I. State avogadrow’s law ?
Ii. Calculate the number if oxygen molecules required to convert 7.50dm³ of SO2
Measured at s.t.p to SO3
2SO2(g)+O2(g)=2SO3(g).
(Molar volume of gas = 22.4 dm3, avogadro’s number =6.02×10²³).

(b)i. Give the valancy of chlorine,oxygen and nitrogen in the following compounds
I. NaCl
II. Na2O
III. Na3N
II. Give two importance of salting out in soap production.

(c)i. Give two exanples of basic oxides
ii. Why are acidic oxide also called acid anhydrides?
iii. Give two chemical properties of oxygen.

(d)i. What are mono saccharides ?.
Ii. Mention two examples of mono saccharides

(e)i. Defined the following terms :
I. Pollution
II. Pollutant
ii. List three example of non biodegradable pollutants
iii. From the equation below
CaC2(s)+2H2O(I)=Ca(OH)+C2H2(g).
Calculate the volume of ethyne produced at s.t.p from 3.2g of calcium carbide
{Ca=40,C=12, O=16H=1, molar volume at s.t.p=22.4dm³molh-¹].

3.

(a)i. what is sublimation ?.
iI. Mention two substance of sublime.

(b). A scientist observed at s.t.p that a certain sample of water boiled at 78°C, instead of
100°C.
I.what I’d ms the reason fir the un usual boiling point observed?.
ii. Name a rechnique that can be used to ensure it boils at 100°C.
iii. What is the equivalent in kelvin of the temperature observed?.

(C) i. State any two conditions for rusting to take place.
ii. Write an equation for the effect of heat on trioxonitrate of a trivalent element .
iij. State any three tyoes of colloidal dispersion.

(d). 6.203g of NaCO3.X H2O was dissolved in water and the solution made up to 1000cm³ if 25.00 cm3of this solution requires 20.50cm³ of 0.122 moldm-³ hydro chloric acid for complete neutralization, calculate the mass of the hydrated salt .
Na2CO3.XH2O(aq)+2HCl(aq)—2NaCl(aq)+XH2O(l)+H2O(l)CO2(g)
(Na=23,C=12,O=16,H=1, Cl=35.5).

(e). A metal has electronic configuration 1s² 2s² 2p6 3s² 3p6 4s¹.
I. Name the metal
ii. Which period does the metal belongm
iii. Which group dies the metal belong?
iv. Give the product of the reaction of the metal with cold water.

4.

(a). Write the half cell equation for the:
I. Oxidation reaction
II. Reduction reaction

(b)i. State two differences between the the compounds and (FeS) and a mixture of
Fr and S.
II. Given that 6P, 13Q, ans and 15R, are element of the periodic table .
Which of the element (s):
I.is a metal
II. Has the highest boiling point
III. Are non metals
Iv. Belong ro the same period.

(C)i. A gas occupies a volume of 300cm³at 410mmHg. What would be its pressure
When the volume is deceased to 130cm³ at constant temperature?.
ii. Write a balance equation to show that carbon act as a reducing agent.

Also read: Neco Biology Questions And Answers 2023