JAMB Past Questions and Answers - Page 1520

7,596.

An element X has electron configuration 1s2 2s2 2p6 3s2 3p5. Which of the following statements is correct about the element?

A.

lt has a completely filled p-orbital

B.

lt has 5 electrons in its outermost shell.

C.

lt belongs to group ll on the periodic table

D.

lt is a halogen

Correct answer is D

No explanation has been provided for this answer.

7,597.

200 cm3 of a gas at 25oC exerts a pressure of 700 mmHg. Calculate its pressure if its volume increase 350 cm3 at 75oC.

A.

342.53 mmHg

B.

1430.54 mmHg

C.

467.11 mmHg

D.

400.00 mmHg

Correct answer is C

\(\frac{p 1V 1}T 1\) = \(\frac{P 2V 2}{T 2}\) \(\frac{700x200}{298}\) = \(\frac{P2X 350}{348}\) P2 = \(\frac{700x200x348}{298x350}\) = 467.11mmHg

7,598.

A gas X diffuses twice as fast as gas Y. if the relative molecular mass of X is 32, calculate the relative molecular mass of Y.

A.

128

B.

8

C.

16

D.

64

Correct answer is A

\(\frac{RY}{RX}\) = \(\frac{\sqrt{My}}{\sqrt{My}}\) 1/2 = \(\frac{\sqrt{32}}{\sqrt{y}}\) \(\frac{32}{y}\) = 1/4
Y = \(\frac{32x4}{1}\) = 128

7,599.

What is the percentage of sulphur in sulphur (IV) oxide?

A.

66%

B.

25%

C.

40%

D.

50%

Correct answer is D

molar mass of SO 2=64 :.%S=32/64 x 100 = 50%

7,600.

A mixture is different from a compound because

A.

the properties of a compound are those of its individual constituents while those of a mixture differ from its constituents

B.

a mixture is always homogeneous while a compound is not

C.

the constituent of a compound are chemically bound together while those of a mixture are not

D.

a mixture can be represented by a chemical formula while a compound cannot

Correct answer is C

No explanation has been provided for this answer.