JAMB Physics Past Questions & Answers - Page 361

1,801.

Which of the following will be applied when a metal Y is used to electroplate another metal X in electrolysis?

A.

X is the anode and very high current is used

B.

X is the anode and Y is the cathode

C.

Y is the cathode and X is the anode

D.

Y is the anode and very high current is used

Correct answer is D

Metals and hydrogen are deposited at the cathode, while non-metals and oxygen are deposited on the anode
∴ metals Y will form the anode which is deposited at the cathode made of x

1,802.

If the threshold frequency for tungsten is 1.3 x 1015Hz, what is its work function?


[H = 6.6 x 10-34 Js]

A.

8.58 x 10-19 J

B.

8.50 x 10-15 J

C.

8.58 x 10-17 J

D.

8.85 x 10-18

Correct answer is A

Work function, w = hfo 6.6 x 10-34 x 1.3 x 1015
= 8.58 x 10-19

1,803.

The electrical properties of germanium can be altered drastically by the addition of impurity. This process is referred to as

A.

saturation

B.

bonding

C.

amplification

D.

dopping

Correct answer is D

No explanation has been provided for this answer.

1,804.

A radioactive isotope has a decay constant of 10-5s4. Calculate half life

A.

6.93 x 10-5s

B.

6.93 x 105s

C.

6.93 x104s

D.

6.93 x 10-4s

Correct answer is C

T (1)/2 = (0.693)/λ = (0.693)/10-5
= 0.693 x 105
= 6.93 x 104 sec

1,805.

The bond between silicon and germanium is

A.

covalent

B.

ionic

C.

dative

D.

electrovalent

Correct answer is A

No explanation has been provided for this answer.