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Chemistry Past Questions

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2,505 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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2,505 questions

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Question 581

jamb 2007

Cu\(^{2+}\)(aq) + 4NH\(_3\)(g) ↔ [Cu(NH\(_3\))\(_4\)]\(^{2+}\)(aq)
In the reaction above, what is the effect of precipitating Cu\(^{2+}\)(aq) as CuS(s)?

ANH_3(g) concentration will decrease

Bmore NH_3(g)

CThe equilibrium will shift to the right

DThere will be no effect

View Explanation & Discuss

Question 582

jamb 2007

The tincture of iodine means iodine dissolved in

Aethanol and water

Bbromine chloride

Cchlorine water

Dwater

View Explanation & Discuss

Question 583

jamb 2007

Na\(_2\)S\(_2\)O\(_3\)(aq) + 2HCl(aq) → 2NaCl(aq) + H\(_2\)O(l)
Which of the following would introduce the greatest increase in the rate of the chemical reaction above?

AAn increase in temperature and decrease in the concentration of the reactant

BA decrease in the volume and increase in the pressure of the reactant

CA decrease in the temperature and an incease in the concentration of the reactant

DAn increase in temperature and an increase in the concentration of the reactant

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Question 584

jamb 2007

The reddish-brown rust on iron roofing sheets consists of

AFe³⁺(H₂O)₆

BFeO.H₂O

CFe₂O₃.3H₂O

DFe₃O₄.2H₂O

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Question 585

jamb 2007

The soft solder used for welding and plumbing is alloy of

Alead and tin

Biron and tin

Clead and zinc

Diron and zinc

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Question 586

jamb 2007

A solution which on treatment with hydrochloric acid produces a colourless, odourless gas which turns lime water milky is most likely to be a

Atrioxonitrate (V)

Bchloride

Ctrioxocarbonate (IV)

Dhydroxide

View Explanation & Discuss

Question 587

jamb 2007

When calcium oxide is heated with carbon, the oxide will

Abe converted to carbide

Bbe converted to the trioxocarbonate (IV) salt

Cdecompose to the metal

Dmelt, producing carbon (IV) oxide

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Question 588

jamb 2007

An element used in the production of matches is

Anitrogen

Baluminium

Ccopper

Dsulphur

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Question 589

jamb 2007

Trioxonitrate (V) acid is not used for preparing hydrogen gas from metals because it

Ais strongly oxidizing

Bis volatile

Crenders the metal passive

Dforms a layer of oxide on the metal

View Explanation & Discuss

Question 590

jamb 2006

In the diagram above, the respective activation energies for the catalyzed and uncatalyzed reactions in kJ are

A45 and 50

B50 and 45

C30 and 35

D40 and 45

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Question 591

jamb 2006

Which of the following functional groups will give gas bubbles when treated with a saturated solution of sodium hydrogen trioxocarbonate (IV)?

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Question 592

jamb 2006

2-methylbut-2-ene has the structure

View Explanation & Discuss

Question 593

jamb 2006

The oxidation of the compound above produces

A2-butanone

B2-butanal

C3-butanal

D3-butanone

View Explanation & Discuss

Question 594

jamb 2006

In the diagram above, mixture Y is

ANH₄NO_3(s) + CaSO_4(s),/sub>

BNH₄Cl_(s) + NaNO_2(s)

CNH₄NO_2(s) + Na₂SO_4(s)

DNH₄Cl_(s) + Ca(OH)_2(s)

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Question 595

jamb 2006

In the diagram above, gas X is

Ahydrogen

Bchlorine

Coxygen

Dhydrogen chloride

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Question 596

jamb 2006

5SO\(_2\)(g) + 2KMnO\(_4\)(aq) + 2H\(_2\)O(l) → K\(_2\)SO\(_4\) + 2MnSO\(_4\)(aq) + 2H\(_2\)SO\(_4\)(aq)
In the reaction above, the products give a

Apurple solution

Bpurple precipitate

Ccolourless precipitate

Dcolourless solution

View Explanation & Discuss

Question 597

jamb 2006

If the heat of combustion of hydrogen is -285.8kJ,
What is the heat of formation of water?

A+571.6 kJ

B-571.6 kJ

C-285.8 kJ

D+285.8 kJ

View Explanation & Discuss

Question 598

jamb 2006

Na\(_2\)CO\(_3\)(g) + 2HCl(aq) → 2NaCl(aq) + H\(_2\)O(l) + CO\(_2\)(g)
How many moles of sodium trioxocarbonate (IV) are there in a 25 cm\(^3\) solution which required 10cm\(^3\) of 0.05 mol dm\(^3\) hydrochloric acid solution to neutralize it?

A1.000 mole

B0.100 mole

C0.010 mole`

D0.111 mole

View Explanation & Discuss

Question 599

jamb 2006

In the electrolysis of CuSO\(_4\)(g) using platinum electrodes, the reaction at the anode is

A4H⁺ + 4e^- → 2H₂

B4OH^- + 4e^- → 2H₂O + O₂

C2OH - 2e^- → 2OH

D2OH^- + 2OH^- → 2H₂O + O₂

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Question 600

jamb 2006

In which of the following is the oxidation number of sulphur equal to - 2?

ASO₃

BS₈

CH₂S

DSO₂

View Explanation & Discuss

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