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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 1071

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

View Explanation & Discuss

Question 1072

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

View Explanation & Discuss

Question 1073

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

View Explanation & Discuss

Question 1074

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₊₊

View Explanation & Discuss

Question 1075

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 1076

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

View Explanation & Discuss

Question 1077

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

View Explanation & Discuss

Question 1078

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 1079

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 1080

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

View Explanation & Discuss

Question 1081

jamb 1985

Aan alkene

Ban alkane

Can alkyne

Dtetrachloromethane

Edichloromethane

View Explanation & Discuss

Question 1082

jamb 1985

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

ACarbon

BAir

CWater

DOxygen

EHydrogen

View Explanation & Discuss

Question 1083

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

View Explanation & Discuss

Question 1084

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

View Explanation & Discuss

Question 1085

jamb 1985

Tetraoxosulphate (IV) ions are finally tested using?

Aacidified silver nitrate

Bacidified barium chloride

Clime-water

Ddilute hydrochloric acid

Eacidified lead nitrate

View Explanation & Discuss

Question 1086

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

View Explanation & Discuss

Question 1087

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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Question 1088

jamb 1985

A man suspected of being drunk is made to pass his breath into acidified potassium dichlormate solution. If his breath carries a significant level of ethanol, the final colour of the solution is?

Apink

Bpurple

Corange

Dblue-black

Egreen

View Explanation & Discuss

Question 1089

jamb 1985

Which of the following is used in the manufacture of bleaching powder?

ASulphur dioxide

BChlorine

CHydrogen tetraoxosulphate (VI)

DHydrogen sulphide

ENitrogen dioxide

View Explanation & Discuss

Question 1090

jamb 1985

Complete hydrogenation of ethyne yields?

Abenzene

Bmethane

Cethane

Dethene

Epropane

View Explanation & Discuss

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