Electronics and Communication Engineering - Digital Electronics

6. 

With four Boolean variables, how many Boolean expressions can be performed?

A. 16
B. 256
C. 1024 (1 K)
D. 64K (64 x 1024)

Answer: Option D

Explanation:

224 = 216.


7. 

A + (B . C) =

A. A . B + C
B. A . B + A . C
C. A
D. (A + B) . (A + C)

Answer: Option D

Explanation:

This is distributive law.


8. 

To count 1000 bottles in a milk plant, the minimum number of flip flops requires is

A. 12
B. 10
C. 8
D. 6

Answer: Option B

Explanation:

20 = 512 and 210 = 1024 Hence at least 10 flip-flops are required.


9. 

Decimal 8 in excess-3 code =

A. 1000
B. 1001
C. 1011
D. 1111

Answer: Option C

Explanation:

Decimal 8 in excess 3 code = decimal 11 = 1011 in binary.


10. 

The inputs to a 3 bit binary adder are 1112 and 1102. The output will be

A. 101
B. 1101
C. 1111
D. 1110

Answer: Option B

Explanation:

Rules for binary addition.

0 + 0 = 0

0 + 1 = 1 + 0 = 1

1 + 1 = 10

i.e., 1 + 1 equals 0 with a carry of 1 to next higher column. 1 + 1 + 1 = 11

i.e., 1 + 1 + 1 equals 1 with a carry of 1 to next higher column.