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.

926.

What mass of copper in gram would be deposited by a current of 1.00ampere passing for 965 seconds through copper(II) tertraoxosulphate (VI) solution? [Cu 63.5; If = 96500c]

A.

0.32

B.

0.64

C.

3.18

D.

6.35

E.

9.65

View answer & explanation

Correct answer is A

Recall that two faradays ( 2 X 96500 ) will be required to discharge 1 mole of a divalent ion like Cu.

2 X 96500 will deposit 63.5g of Cu

And 965C wiil deposit  x-grams

CROSS MULTIPLY

(965 X 63.5) ÷ ( 2 X 96500)

= 0.3175

927.

How many zones are present in a luminous Bunsen burner flame?

A.

2

B.

3

C.

4

D.

5

E.

6

View answer & explanation

Correct answer is C

The luminous bunsen burner flame has four zones namely:

  • Dark zone/ zone of unburnt gas; burning of the gas does not take place here, it is dark and cool.
  • Luminous yellow zone; the gas burns in this zone but not completely because of limited air. Tiny particles glow in this region to give out light.
  • Thin outer zone; the zone is colorless and gas burns completely due to plenty of air.
  • Blue zone; this zone receives plenty of air and burning is more complete than in the luminous zone.

928.

When air is passed through alkaline pyrogallol and then lime water, the gases left are

A.

nitrogen and carbon (IV) oxide

B.

nitrogen and noble gases

C.

nitrogen and oxygen

D.

nitrogen, carbon (VI) oxide and noble gases

E.

the noble gases

View answer & explanation

Correct answer is B

No explanation has been provided for this answer.

929.

A salt which loses its mass when exposed to air is

A.

deliquescent

B.

effervescent

C.

Efflorescent

D.

fluorescent

E.

hygroscopic

View answer & explanation

Correct answer is C

No explanation has been provided for this answer.

930.

Atomic size decreases

A.

across a period from left to right

B.

across a period from right to left

C.

diagonally down the group

D.

down a group

E.

with decrease in atomic number

View answer & explanation

Correct answer is A

No explanation has been provided for this answer.


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