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Chemistry Past Questions

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51 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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Past Questions

51 questions

Question 1 of 20 51 total questions

Question 11

jamb 1985

The diagram shown above represents the solubility curves of two salts, X and Y, in water, use this diagram to answer the question. If the molar mass of X is 36 g, the number of moles of X dissolved at 343 K is

A0.2 moles

B0.7 moles

C1.5 moles

D2.0 moles

E3.0 moles

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Question 12

jamb 1985

The diagram shown above represents the solubility curves of two salts, X and Y, in water, use this diagram to answer the question. If 80 g each of X and Y are taken up in 100 g of water at 353 K we shall have

Aonly 10g of X undissolved

Bonly 16 g of Y undissolved

C10 g of X and 16 g of Y undissolved

Dall X and Y dissolved

Eall X and Y undissolved

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Question 13

jamb 1985

The diagram shown above represents the solubility curves of two salts, X and Y, in water, use this diagram to answer the question. At room temperature (300 K)

AY is twice as soluble as X

BX is twice as soluble as Y

CX and Y are soluble to the same extent

DX is three times as soluble as Y

EY is three times as soluble as X

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Question 14

jamb 1985

Figure 1 above shows part of the periodic Table which of the elements belongs to the p-block?

AS, T and U

BV, W and X

CS and T only

DP, Q and R

EV, W, X and S

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Question 15

jamb 1985

The function of sulphur during vulcanization rubber is to?

Aact as catalyst for the polymerization of rubber molecules

Bconvert rubber from thermosetting to thermo plastics polymer

Cfrom chains which bind rubber molecules together

Dbreak down rubber polyer

Eshorten the chain length of rubber polyer

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Question 16

jamb 1985

Which of the following roles does sodium chloride play in soap preparation? It

Areacts with glycerol

Bpurifies the soap

Caccelerates the decomposition of the fat or oil

Dseparates the soap from the glycerol

Econverts the fatty acid to its sodium salt

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Question 17

jamb 1985

An aqueous solution of an inorganic salt gave white precipitate (i) soluble in excess aqueous NaOH (ii) insoluble in excess aqueous NH\(_3\) (iii) with dilute HCl. The cation present in the inorganic salt is?

ANa⁺

BCa⁺⁺

CZn⁺⁺

DAl⁺⁺⁺

EPb₊₊

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Question 18

jamb 1985

The process involved in the conversion of an oil into margarine is known as?

Ahydrogenation

Bcondensation

Cpyrolysis

Ddehydration

Ecracking

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Question 19

jamb 1985

Addition of dilute hydrochloride acid to an aqueous solution of a crystalline salt yield a yellow precipitate and a gas which turned dichromate paper green. The crystalline salt was probably?

ANa₂SO₄

BNa₂S

CNa₂S₂O₃.5H₂O

DNa₂CO₃

ENaHCO₃

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Question 20

jamb 1985

When marble is heated to about 1473 K, another white solid is obtained which reacts vigorously with water to give an alkaline solution. The solution contains?

ANaOH

BKOH

CMg(OH)₂

DZn(OH)₂

ECa(OH)₂

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Question 21

jamb 1985

The atomic number of an element whose cation, X2+, has the ground state electronic configuration 1s22s22p63s22p6 is?

A16

B18

C20

D22

E24

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Question 22

jamb 1985

Which of the following compounds is NOT the correct product formed when the parent metals is heated in air?

ACalcium oxide (CaO)

BSodium oxide (Na₂O)

CCopper (ll) oxide (CuO)

DTri-iron tetroxide (Fe₃O₄)

EAluminium oxide (Al₂O₃)

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Question 23

jamb 1985

A colourless organic compound X was burnt in excess air to give two colourless and odourless gases, Y and Z, as products. X does not decolorize blue bromine vapour, Y turns lime milky while Z gives a blue colour with copper (ll) tetraoxosulphate (IV).
Y and Z are respectively?

ACO₂ and NH₃

BCO and NH₃

CSO₂ and H₂O

DCO₂ and H₂O

ESO₂ and NH₃

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Question 24

jamb 1985

Aan alkene

Ban alkane

Can alkyne

Dtetrachloromethane

Edichloromethane

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Question 25

jamb 1985

Which of the following substances is the most abundant in the universe?

ACarbon

BAir

CWater

DOxygen

EHydrogen

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Question 26

jamb 1985

Solid sodium hydroxide on exposure to air absorbs a gas and ultimately gives another alkaline substance with the molecular formula?

ANaOH.H₂O

BNaOH.N₂

CNa\(_2\)CO\(_3\)

DNaHCO₃

ENaNO₃

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Question 27

jamb 1985

An organic compound decolourized acidified KMnO₄ solution but failed to react with ammoniacal silver nitrate solution. The organic compound is likely to be?

Aa carbonxylic acid

Ban alkane

Can alkene

Dan alkyne

Ean akanone

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Question 28

jamb 1985

Tetraoxosulphate (IV) ions are finally tested using?

Aacidified silver nitrate

Bacidified barium chloride

Clime-water

Ddilute hydrochloric acid

Eacidified lead nitrate

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Question 29

jamb 1985

The energy change (ΔH) for the reaction CO(g) + (1)/(2)O_2(g) → is?

(ΔHi(CO) = -110.4 kJ mol^-) (ΔHi(CO₂) = -393 kJ mol^-)

A-503.7 kJ

B+503.7kJ

C-282.9 kJ

D+282.9 kJ

E+393.3 kJ

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Question 30

jamb 1985

When pollen grains are suspended in water and viewed through a microscope, they appear to be in a state of constant but erratic motion. This is due to?

Aconvection currents

Bsmall changes

Csmall changes in temperature

Da chemical reaction between the pollen grain and water

Ethe bombardment of the pollen grains by molecules of water

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