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Chemistry Past Questions

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4,306 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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4,306 questions

Question 1 of 20 4,306 total questions

Question 1951

jamb 1986

A substance Z reacts with NaOH to give salt and water only. When Z is treated with dilute HCl, a gas is evolved which gives a yellow suspension on passing into concentrated H₂SO₄. Substance Z is?

ANaHS

BNa₂SO₃

CNa₂S

DNaHSO₃

View Explanation & Discuss

Question 1952

jamb 1986

When chlorine is passed into water and subsequently exposed to sunlight, the gas evolved is?

AHCl

BHOCl

CO₂

DCl₂O

View Explanation & Discuss

Question 1953

jamb 1986

Which of the following sulphides is insoluble in dilute HCl?

ANa₂S

BZnS

CCuS

DFeS

View Explanation & Discuss

Question 1954

jamb 1986

Which of the following metals does NOT form a stable trioxocarbonate (IV)?

AFe

BAl

CZn

DPb

Enone of the options is correct

View Explanation & Discuss

Question 1955

jamb 1986

In the course of an experiment, two gases X and Y were produced. X turned wet lead ethanoate to black and Y bleached moist litmus paper. What are the element(s) in each of the gases X and Y respectively?

AH and S;Cl

BH and O;Cl

CH and S;C and O

DH and Cl;S and O

View Explanation & Discuss

Question 1956

jamb 1986

Which of the following will react further with oxygen to form higher oxide?

ANO and H₂O

BCO and CO₂

CSO₂ and NO

DCO₂ and H₂O

View Explanation & Discuss

Question 1957

jamb 1986

Oxygen-demanding waste are considered to be a water pollutant because they?

Adeplete oxygen which is necessary for the survival of aquatic organism

Bincrease oxygen which is necessary for survival of aquatic organism

Cincrease other gaseous substances which are necessary for the survival of aquatic organisms

Ddeplete other gaseous species which is necessary for the survival of aquatic organisms

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Question 1958

jamb 1986

The exhaust fumes from a garage in a place that uses petrol of high sulphur content are bound to contain?

ACO and SO₃

BCO and SO₂

CCO,SO₂ and SO₃

DCO and H₂S

View Explanation & Discuss

Question 1959

jamb 1986

When steam is passed through red hot carbon, which of the following are produced?

AHydrogen oxygen and carbon (IV) oxide

BHydrogen and carbon (IV) oxide

CHydrogen and carbon (II) oxide

DHydrogen and trioxocarbonate (IV) acid

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Question 1960

jamb 1986

The reaction Mg + H₂O → MgO + H₂ takes place only in the presence of?

Aexcess Mg ribbon

Bexcess cold water

Cvery hot water

Dsteam

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Question 1961

jamb 1986

The approximate volume of air containing 10cm³ of oxygen is?

A20 cm³

B25 cm³

C50 cm³

D100 cm³

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Question 1962

jamb 1986

What is the consequences of increasing pressure on the equilibrium reaction ZnO(s) + H2(g) Zn(s) + H2O(I)?

AThe equilibrium is driven to the left

BThe equilibrium is driven to the right

CThere is no effect

DMore ZnO is produced

View Explanation & Discuss

Question 1963

jamb 1986

20 cm³ of 1.0 molar NH₄OH solution when neutralized with 20.05cm³ of 0.1 molar HCl liberated -102 joules of heat. Calculate the heat of neutralization of NH₄OH?

A-51.O KJ mol^-

B+57.3 KJ mol^-

C+57.O KJ mol^-

D+51.0 KJ mol^-

View Explanation & Discuss

Question 1964

jamb 1986

Which of these represents a redox reaction?

AAgNO₃ + NaCl → AgCAl + NaNO₃

BH₂S + Pb(NO₃) → PbS + 2HNO₃

CCaCO₃ → CaO + CO₂

DZn + 2HCl → ZnCl₂ + H₂

View Explanation & Discuss

Question 1965

jamb 1986

How many coulombs of electricity are passed through a solution in which 6.5 amperes are allowed to run for 1.0 hour?

A3.90 x 10² coulombs

B5.50 x 10³ coulombs

C6.54 x 10³ coulombs

D2.34 x 10⁴ coulombs

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Question 1966

jamb 1986

Which of the following solutions will conduct the least amount of electricity?

A2.00 M aqueous solution of NaOH

B0.01 M aqueous solution of NaOH

C0.01 M aqueous solution of hexanoic acid

D0.01 M aqueous solution of sugar

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Question 1967

jamb 1986

Which of the following is an acidic salt?

ANaHSO₄

BNa₂SO₄

CCH₃CO₂Na

DNa₂S

View Explanation & Discuss

Question 1968

jamb 1986

Which of the following salts when dissolved in water will NOT give the corresponding pH value?

ANaHSO₄, pH < 5

BNa₂CO₃, pH > 8

CNa₂Cl,pH = 7

DNaHCO

View Explanation & Discuss

Question 1969

waec 1985

A sample of air that has been passed through caustic potash will

Acontain more oxygen than nitrogen

Brekindle a glowing splint

Chave no action on lime water

Dcontain no water vapour

Ebe free of noble gases

View Explanation & Discuss

Question 1970

waec 1985

Chlorine is prepared on a large scale by the

Aelectrolysis of concentrated sodium chloride solution

Baction of manganese (IV) oxide on hot concentrated hydrochloric acid

Caction of concentrated tetraoxosulphate (IV) acid on sodium chloride

Doxidation of concentrated hydrochloric acid with potassium tetraxosulphate (VII)

Eaction of dilute mineral acids on bleaching powder

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