JAMB Chemistry Past Questions & Answers - Page 69

341.

How many atoms are present in 6.0g of magnesium? [Mg = 24, N.A = 6.02 x 10 \(^{23}\)mol]

A.

1.20 x 10\(^{22}\)

B.

2.4 x 10\(^{22}\)

C.

1.51 x 10\(^{22}\)

D.

3.02 x 10\(^{22}\)

Correct answer is C

No explanation has been provided for this answer.

342.

What is the concentration of a solution containing 2g of NaOH in 100cm3 of solution? [Na = 23, O =16, H = 1]

A.

0.40 moldm\(^{-3}\)

B.

0.50 moldm\(^{-3}\)

C.

0.05 moldm\(^{-3}\)

D.

0.30 moldm\(^{-3}\)

Correct answer is B

No explanation has been provided for this answer.

344.

The lUPAC name for

A.

1-methyl pentane

B.

3-methylbutane

C.

2-methylbutane

D.

1-dimethyl propane

Correct answer is C

The longest carbon chain is butane, with one substituent attached at carbon number 2

therefore the compound is named  2-methyl butane

345.

If one of the following oxides is heated with hydrogen or carbon using a bunsen burner. it is not reduced to the metal, Which one is it?

A.

lead oxide

B.

Magnesium oxide

C.

Copper oxide

D.

Tin oxide

Correct answer is B

The oxides of Potassium, Sodium, Calcium, and Magnesium are not reduced when they react with carbon and hydrogen.