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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 2111

jamb 1979

Bronze is an alloy of

Acopper, zinc and nickel

Baluminium and copper

Ccopper and zinc

Dtin and zinc

Etin and copper

View Explanation & Discuss

Question 2112

jamb 1979

Two metallic ions associated with hard water are

Acopper and zinc

Bmagnesium and silver

Ccalcium and magnesium

Dpotassium and tin

Esodium and lead

View Explanation & Discuss

Question 2113

jamb 1979

Hydrogenation may be effected by

Athe removal of hydrogen from an alkane in the presence of a catalyst

Bthe addition of hydrogen to an alkane in the presence of a catalyst

Cthe addition of hydrogen to an alkyne

Dthe removal of hydrogen from an alkyne

Ethe addition of hydrogen to an ethyl alcohol

View Explanation & Discuss

Question 2114

jamb 1979

The solution of a sample in a tube will be identified as a chloride if it gives

Aa white precipitate on addition of AgNO₃ and barium chloride solutions

Ba white precipiate when acidified with HCI, and then AgNO₃ solution added

Ca white precipitate when acidified with dilute HNO₃ and then AgNO₃ solution added

Da white precipitate when acidified with dilute H₂SO₄ and then barium nitrate solution added

Ea pungent smell of chlorine gas when dilute HCI and MnO₂ are added

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Question 2115

jamb 1979

The reaction 3C(s) + 2Fe₂O₃(s) = 4Fe(s) + 3CO₂(g): \(\Delta\)H =46.0 kJ is

Aisothermic

Badiabatic

Cisobaric

Dendothermic

Eexothermic

View Explanation & Discuss

Question 2116

jamb 1979

the vapour density of a gas may be defined as

Athe mass of a unit volume of the gas compared to an equal volume of water vapour

Bthe mass of a unit volume of the gas compared to an equal volume of hydrogen

Cthe mass of a unit volume of the gas compared to an equal volume of oxygen

Dthe mass of a unit volume of the gas minus the vapour pressure of water

Etwo times the relative molecular mass of the gas

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Question 2117

jamb 1979

Which of the following statements is true?

Aan increase in the temperature of a given mass of gas increases the number of gas molecules

Ban increase in the temperature of the gas does not affect the kinetic energy

Can increase in the pressure of the gas is proportional to the increase in volume

Da increase in the pressure of a gas is proportional to the decrease in volume at constant temperature

Ea decrease in the pressure of the gas decreases the number of gas molecules present

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Question 2118

jamb 1979

In the manufacture of iron in the blast furnace, iron (lll) oxide is mixed with coke and limestone, and different reactions occur in the process. Which of the following statements is true with respect to these reactions?

Athe coke is a powerful reducing agent and easily converts the iron oxide to iron

Bthe calcuim carbonate reacts with SiO₂ an earthly impurity in the ore, to from calcuim silicate

Cthe coke will react with the iron produced to form steel

Dall the carbondioxide required in the process comes from the decomposition of the calcium carbonate

Ethe calcium carbonate decomposes to give calcium oxide, which then forms calcium silicate with the earthly impurity

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Question 2119

jamb 1979

Weighed salts Y and Z were left exposed in the laboratory overnight. In the morning Y had gained weight, and Z had become liquid. What conclusion could be drawn about the nature of the two salts?

AZ is efflorescent

BY and Z are efflorescent

CY and Z are deliquescent

DY and Z are hygroscopic

EY is deliquescent

View Explanation & Discuss

Question 2120

jamb 1979

The reaction between hydrogen and iodine may be represented by the equation H₂(g)+ I₂(g) → 2HI(g), and is exothermic. Therefore

Aan increase in temperature favours the forword reaction

Ban increase in pressure favours the backward reaction

Cboth pressure and temperature muct be increased to favour the forward reaction

Da decrease in temperature will favour the forward reaction

Ea decrease in pressure and an increase in temperature will favour the forward reaction

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Question 2121

jamb 1979

Starch can be converted to ethyl alcohol by

Adistillation

Bfermentation

Cisomerization

Dcracking

Ecooking

View Explanation & Discuss

Question 2122

jamb 1979

Calcium hydroxide and ammonium chloride when heated together will give an important product. This compound may be obtained dry by

Adissolving it in water, recrystallizing it and then drying in the oven

Bpassing it through a concentrated aqueous solution of sodium hydroxide

Cpassing it through calcium oxide

Dpassing it through concentrated sulphuric acid

Epassing it through anhydrous calcium choride

View Explanation & Discuss

Question 2123

jamb 1979

In which of the following reactions is sulphur dioxide acting as an oxidizing agent?

ASO ₂ + 2HNO₃ →H₂SO₄ + NO₂ + Heat

B2SO₂ + 2H₂O + O₂→ 2H₂SO₄

CSO₂ + 2H₂O + CI₂→ H₂SO₄ + 2HCI

DSO₂ + 2H₂S → 3S + 2H₂O

ESO₂ + H₂O → H₂SO₃

View Explanation & Discuss

Question 2124

jamb 1979

An anhydride is?

Aa compound wich has no water of crystallization

Ban oxide whose solution in water has a PH greater than 7

Can oxide whose solution in water has a PH less than 7

Dan oxide that has hydrogen atoms

Ean amphoteric oxide

View Explanation & Discuss

Question 2125

jamb 1979

In the redox reaction\( 2Fe^{2+} + CI_2 → 2Fe^{3+} + 2Cl^-\)

ACl₂ is reduced because it has lost electrons

BCl₂ is reduced because its oxidation number has decreased

CCl₂ is reduced because its molecule is change to two ions

DFe²⁺ is reduced because it has lost electrons

EFe²⁺ is reduced because it has gained electrons

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Question 2126

jamb 1979

In the extraction of aluminum from purified bauxite by electrolysis, cryolite is used because

Ait makes bauxite a better conductor of electricity

Bit makes bauxite melt at a lower temperature

Cit makes aluminium purer

Dit prevents aluminium from getting oxidized

Eit protects the carbon electrodes used in the process

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Question 2127

jamb 1979

Which one of these compounds will NOT give an oxygen gas on heating?

AManganese dioxide

BHydrogen peroxide

CZinc nitrate

DSodium nitrate

EAmmonium nitrate

View Explanation & Discuss

Question 2128

jamb 1979

0.1 Faraday of electricity was passed through a solution of copper (ll) sulphate. The maximum weight of copper deposited on the cathode would be [Cu = 64]

A64.0g

B32.0g

C16.0g

D6.4 g

E3.2g

View Explanation & Discuss

Question 2129

jamb 1979

Indicate which of the following statements is not true as we move from left to right along the periodic Table:

Aatomic number of elements increases

Batomic mass of elements increases

Celectropositive character of elements increases

Delectronegative character of elements increases

Enumber of electrons in the outermost orbits of element increases

View Explanation & Discuss

Question 2130

jamb 1979

When a piece of charcoal enclosed in a cylinder containing air is ignited

Athe toatl volume of air is increased

Bthe relative amount of oxygen present is increased

Cthe relative amount of nitrogen present is decreased

Dthe relative amount of carbondioxide present is increased

Ethe ratio of oxygen to nitrogen in the system is increased

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