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Chemistry questions and answers

Chemistry Questions and Answers

Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.

441.

How many alkoxyalkanes can be obtained from the molecular formula C4H10O?

A.

4

B.

2

C.

1

D.

3

Correct answer is D

No explanation has been provided for this answer.

442.

The cost of discharging 6.0g of a divalent metal, X from its salt is ₦12.00. What is the cost of discharging 9.0g of a trivalent metal, Y from its salt under the same condition?
[X = 63, Y = 27, 1F = 96,500C]

A.

N12.00

B.

N27.00

C.

N63.00

D.

N95.00

Correct answer is C

For X:  X2+ + 2e X

2F = 63g

xF = 6g

x = 6×263=421F

421F = N12.00

1F = 12421

= N63.00

1F is equivalent to N63.00.

For Y: Y3+ + 3e Y

3F = 27g 

xF = 9g

x = 3×927

= 1F

1F = N63.00

443.

If the cost of electricity required to discharge 10g of an ion X3+ is N20.00, how much would it cost to discharge 6g of ion Y2+?

[1 faraday = 96,500C, atomic masses are X = 27, Y = 24]

A.

N10.00

B.

N6.00

C.

N20.00

D.

N9.00

Correct answer is D

X3+ + 3e X

3F = 27g

xF = 10g

x3=1027x=109F

109F N20.00

1F is equivalent to x

1109=x20

910=x20x=N18.00

1F is equivalent to N18.00.

Y2+ + 2e Y

2F = 24g

xF = 6g

x = 6×224=12F

1F = N18.00

12F = 12×N18.00

= N9.00

444.

Hydrogen diffused through a porous plug

A.

thrice as fast as oxygen

B.

at the same speed as oxygen

C.

four times as fast as oxygen

D.

twice as fast as oxygen

Correct answer is C

Using Graham's Law of Diffusion,

R1R2=m2m1

RHRO=mOmH

RHRO=322

RHRO=16=4

Therefore, hydrogen diffuses 4 times faster than oxygen.

445.

The emission of two successive beta particles from the nucleus ^{32} _{15} P will produce

A.

^{30} _{14}Si

B.

^{32} _{13}Al

C.

^{32} _{17}Cl

D.

^{32} _{16}S

Correct answer is C

^{32} _{15}P \to 2^{0} _{-1}e + ^{a} _{b}X

32 = 2(0) + a

a = 32

15 = 2(-1) + b

b = 15 + 2

b = 17

\therefore ^{a} _{b}X = ^{32} _{17}Cl