JAMB Chemistry Past Questions & Answers - Page 100

496.

How much of magnesium is required to react with 260cm3 of 0.5 M HCl? [Mg = 24]

A.

0.3g

B.

1.5g

C.

2.4g

D.

3.0g

Correct answer is B

No explanation has been provided for this answer.

497.

The number of atoms of chlorine present in 5.85g of NaCl is [Avogaro's Number = 6.02 x 1023]

A.

6.02 x 1022

B.

5.85 x 1023

C.

6.02 x 1023

D.

5.85 x 1024

Correct answer is A

The number of atoms of chloride present in 5.85g of NaCl is 5.85 x 6.0 x 1023

= 6.02 x 1022

498.

10cm3 of hydrogen fluoride gas react with 5cm3 of dinitrogen difluoride gas (N2F2) to form 103 of a single gas. Which of the following is the most likely equation of the reaction?

A.

HF + N2F2 \(\to\) N2HF3

B.

2HF + N2F2 \(\to\) 2NHF2

C.

2HF + N2F2 \(\to\) N2H2F3

D.

HF + 2N2F2 \(\to\) N4HF2

Correct answer is B

No explanation has been provided for this answer.

499.

The Avogadro number of 24g of magnesium is the same as that of

A.

1g of hydrogen molecules

B.

16g of oxygen molecules

C.

32g of oxygen molecules

D.

35.5g of chlorine molecules

Correct answer is C

24mg = 1 mole of magnesium and

32g of O2 = mole of O2

500.

CO(g) + H2O(g) \(\to\) \(CO_{2g}\) + H2(g)  \(\Delta\)H = -4100J. Which of the following factors favour the formation of hydrogen in the above reaction? i. high pressure. ii. low pressure iii. high-temperature iv. use of excess steam

A.

i, iii and iv

B.

iii only

C.

ii, iii and i

D.

iv only

Correct answer is D

i, ii will have no effect because the number of mole of reactants(volume) is equal to the number of mole of the product(volume) and iii will also have no effect since the forward reaction which favours the production of hydrogen is exothermic, therefore, the production of hydrogen will be favored by iv only.