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Chemistry Past Questions

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130 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10

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130 questions

Question 1 of 20 130 total questions

Question 51

jamb 2019

What technique is suitable for separating a binary solution of potassium chloride and potassium trioxochlorate (V)?

AFractional crystallization

BFractional distillation

CFiltration

DEvaporation

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Question 52

jamb 2019

Which of the following does not support the fact that air is a mixture?

Athe constituents of air are in a fixed proportion by mass

Bit cannot be represented with a chemical formula

Cthe constituents of air can be separated by physical by physical means

Dnone of the above

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Question 53

jamb 2019

Which of the following statements about catalyst is false?

Abiological catalysts are called enzymes

Bcatalyst do not appear in the balanced equation

Ccatalyst reduce the activation energy for a reaction

Dcatalysts do not alter the mechanism of the reaction and never appear in the rate low

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Question 54

jamb 2019

The heat of formation of ethene, C\(_2\)H\(_4\) is 50 kJmol\(^{-1}\), and that of ethane, C\(_2\)H\(_6\) is -82kJmol\(^{-1}\). Calculate the heat evolved in the process:

C\(_2\)H\(_4\) + H\(_2\) \(\to\) C\(_2\)H\(_6\)

A-122kJ

B-132kJ

C-88kJ

D-60kJ

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Question 55

jamb 2019

If acidified Potassium Dichromate(VI) (K\(_2\)Cr\(_2\)O\(_7\)) acts as oxidizing agent, color changes from

Ayellow to green

Borange to green

Cyellow to red

Dorange to red

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Question 56

jamb 2019

Which of the following reactions is an oxidation process?

A2H\(^+\) + 2e\(^-\) \(\to\) H\(_2\)

B2O\(^{2-}\) + 4e\(^-\) \(\to\) O\(_2\)

COCl\(^-\) + H\(_2\)O + 2e\(^-\) \(\to\) 2OH\(^-\) + Cl\(^-\)

DCl + e\(^-\) \(\to\) Cl\(^-\)

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Question 57

jamb 2019

For the general equation of the nature
xP + yQ ⇌ mR + nS, the expression for the equilibrium constant is

Ak[P]\(^x\)[Q]\(^y\)

B\(\frac{m[R][S]}{x[P]y[Q]}\)

C\(\frac{[P]^x[Q]^y}{[R]^m[S]^n}\)

D\(\frac{[R]^m[S]^n}{[P]^x[Q]^y}\)

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Question 58

jamb 2019

Consider the reaction
A\(_{(s)}\) + 2B\(_{(g)}\) → 2C\(_{(aq)}\) + D\(_{(g)}\)
What will be the effect of a decrease in pressure on the reaction?

Athe equilibrium will shift

Brate of forward reaction will increase

Crate of backward reaction will increase

Drates of forward and backward reaction are not affected

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Question 59

jamb 2019

Which of the following represents the kind of bonding present in ammonium chloride?

Aionic only

Bcovalent only

Cionic and covalent

Ddative covalent

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Question 60

jamb 2019

When ammonia and hydrogen ion bond together to form ammonium ion, the bond formed is called

Aelectrovalent bond

Bcompound bond

Cionic bond

Dcovalent bond

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Question 61

jamb 2019

The combustion of carbon(II)oxide in oxygen can be represented by equation:
2CO + O\(_2\) → 2CO\(_2\)
Calculate the volume of the resulting mixture at the end of the reaction, if 50cm\(^3\) of carbon(ii)oxide was exploded in 100cm\(^3\) of oxygen

A75cm\(^3\)

B125cm\(^3\)

C100cm\(^3\)

D50cm\(^3\)

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Question 62

jamb 2019

By what amount must the temperature of 200cm\(^3\) of Nitrogen at 27°C be increased to double the pressure if the final volume is 150cm\(^3\) (Assume ideality)

A150°C

B177°C

C75°C

D120°C

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Question 63

jamb 2019

Elements X and Y have electronic configurations 1s\(^2\)2s\(^2\)2p\(^4\) and 1s\(^2\)2s\(^2\)2p\(^6\)3s\(^2\)3p\(^1\) respectively. When they combine, the formula of the compound formed is

AXY

BX\(_2\)Y

CY\(_2\)X\(_3\)

DX\(_2\)Y\(_3\)

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Question 64

jamb 2019

Which of the following statements does not show Rutherford's account of Nuclear Theory? An atom contains a region

Awhich contains protons and neutrons

Bwhich is positively charged

Cwhich is massive and can cause deflection of a few projectiles

Dwhich is very large and in which close to 98% of projectiles pass undeflected

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Question 65

jamb 2019

SO\(_3\) is not directly dissolved in water in the industrial preparation of H\(_2\)SO\(_4\) by the contact process because

ASO\(_3\) is an acidic gas

BAcid is usually added to water and not water to acid

CThe reaction between SO\(_3\) and water is violently exothermic

DSO\(_3\) does not dissolve readily in water

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Question 66

jamb 2019

Which of the following is a set of neutral oxides?

AN\(_2\)O, H\(_2\)O, CO

BN\(_2\)O, SO\(_2\), CO

CN\(_2\)O, Na\(_2\)O, ZnO

DN\(_2\)O, SO\(_3\), NO

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Question 67

jamb 2019

Which process(es) is/are involved in the turning of starch iodide paper blue-black by chlorine gas?

Achlorine attacks the starch to give the blue-black color

Bchlorine attacks the iodide ion to give the blue-black color

Cchlorine oxidizes the iodide ion to produce iodine which attacks the starch to give the blue-black color

Diodine attacks the starch to give the blue-black color

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Question 68

jamb 2019

When chlorine water is exposed to bright sunlight, the following products are formed

AHCl\(_{(aq)}\) and Cl\(_2\)

BHOCl\(_{(aq)}\) and Cl\(_2\)

CHCl\(_{(aq)}\) and O\(_2\)

DHOCl\(_{(aq)}\) and O\(_2\)

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Question 69

jamb 2019

Which of the following alkaline earth metals react more spontaneously with water?

ACalcium

BBeryllium

CMagnesium

DStrontium

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Question 70

jamb 2019

Which of the following metals is the most essential in the regulation of blood volume, blood pressure and osmotic equilibrium?

AZinc

BManganese

CSodium

DIron

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