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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.

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1,091.

An oxidation state of Cr in K2Cr2O7

View answer & explanation

Correct answer is B

The oxidation state of K2Cr2O7 is +6. option A,C,D are the oxidation state of other elements like O7,C14, etc.

$+2 + 2x + (-2\times7) =0$

$2x=12$

$x = +6$

1,092.

A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180, Find the molecular formula [H = 1, C = 12, O = 16)

CH₂O

C₃H₆O₃

C₆H₁₂O₆

C₆H₁₂O₃

View answer & explanation

Correct answer is C

C = 40%, 40/12 = 3.33
H = 6.7%, 6.7/1 = 6.7
O = 53.3%, 53.3/16 = 3.33
C = 3.33/3.33 = 1
H = 6.7/3.33 = 2
O = 3.33/3.33 = 1
(CH2O)n = 180
(12 + 2 + 16)n = 180
30n = 180
n = 6
= C6H12O6

1,093.

What volume of 0.5mldm³ H₂SO₄ will exactly neutralize 20cm³ of 0.1moldm³ NaOH Solution?

2.0cm³

5.0cm³

6.8cm³

8.3cm³

View answer & explanation

Correct answer is A

2NaOH + H2SO4 → Na2SO4 + 2H2O
CaVa) ÷ (CbVb) = ratio of acid / ratio of base
0.5Va ÷ (0.1 × 20) = ½
Va = 2.0cm3

1,094.

The energy value of petrol can be determined by

Bomb calorimeter

Catalytic cracker

Fractionating column

Thermometer

View answer & explanation

Correct answer is C

Fractionating column contains petrol with different densities.

1,095.

The basic particles from which matter could be made up of are as follow, except?

Salt

Atom

Ion

Molecule

View answer & explanation

Correct answer is A

Salt is a chemical used for varieties of purposes, so it’s not part of matter, Atom being the smallest part of molecule and ion are charge which are part of matter