21. Which of the following is false regarding the evaluation
of computer programming language?

(1) Application oriented feature

(2) Efficiency and readability

(3) Software Development

(4) Hardware maintenance cost

**Answer : 1**

22. The symmetric deference of two sets s1 and s2 is defined
as

S1 Θ S2={x|x € S1 or x € S2, but x is not both S1 and
S2}

The nor of two language is defined as

Nor (L1,L2)={w|w ¢ L1 and W ¢ L2}.

Which of the following is correct?

(1) The family of regular language is closed under symmetric difference
but not closed under nor.

(2) The family of regular language is closed under nor but not
closed under symmetric difference.

(3) The family of regular language are closed under both symmetric
difference and nor.

(4) The family of regular
language are not closed under both symmetric difference and nor.

**Answer : 3**

23. The regular expression for the component of the language
L={AnAm|n>=4,m<=3} is :

(1) (ƛ a+aa+aaa)b*a*bbbb*+(a+b)*ba(a+b)*

(2) (ƛ+a+aa+aaa) b*+a*bbbbb*+(a+b)*ab(a+b)*

(3) (ƛ +a+aa+aaa)+a*bbbbb*+(a+b)*ab(a+)*

(4) (ƛ+a+aa+aaa)b*+a*bbbbb*+(a+b)*ba(a+b)*

**Answer : 2**

24.Consider the following two language :

L1={OiIj|gcd(I,j)=1}

L2 is any subset of 0*

Which of the following is correct ?

(1) L1 is regular and L2 is not regular

(2) l1 IS NOT REGULAR AND l2* IS REGULAR

(3) Both L1 and L2* are regular languages

(4) Both L1 and L2* are not regular

**Answer : 1**

25. if link transmits 4000 frames per second and each slot has 9
bits, the transmission rate of circuit of this TDM is____

(1) 64 Kbps

(2) 32 Mbps

(3) 32 KBPS

(4) 64KBPS

**Answer : 3**

26. Given the following statements:

(A) Frequency division multiplexing is a technique that can be
applied when the bandwidth of a link is greater than combined of signals to be transmitted.

(B) Wavelength division multiplexing (WDM) is an analog
multiplexing technique to combine optical signals

( C) WDM is digital multiplexing technique

(D) TDM is a digital Multiplexing technique

(1) (A),(B) and (D) are true

(2) (A),(B),(C) and (D) are false

(4) (A) , (B) and (D) are true (C) is false

**Answer : 2**

27. A pure ALOHA network transmit 200 bit frame using a shared
channel with 200 KBPS bandwidth . if the system (all station put together)
produces 500 frames per second , then the throughput of the system is ___

(1) 0.384

(1) 0.384

(2) 0.184

(3) 0.286

(4) 0.586

**Answer : 1**

28. Math the following

(a)Block coding (I)
A technique to change analog to digital data

(b)Block coding (II)
Provides synchronization without increasing number of bits

(C) Scrambling (III)
Process of converting digital data to digital signal.

(d) Pulse code modulation (IV)
Provides redundancy to ensure synchronization and inherit error detection

Codes :

(a) (b) (c) (d)

(1) (iv) (iii) (ii) (i)

(2) (iii) (iv) (ii) (i)

(3) (i) (iii) (ii) (iv)

(4) (ii) (i) (iv) (iii)

**Answer : 3**

29. Assume that we need to download text documents at the rate of
100 pages per page minute. A page is a average of 24 lines with 80 characters
in each line and each character requires 8 bit. Then the required bit rate
channel is

(1) 1.636 Kbps

(2) 1.636 Mbps

(3) 3.272 Mbps

(4) 3.272 Kbps

**Answer : 4**

30. Encrypt the plain text message “ EXTRANET” using transposition
cipher technique with the following key :

Using Z as bogus character.

(1) TAXERTZENZ

(2) EXTRANETZZ

(3) EZXZTRZANZET

(4) EXTZRANZETZ

**Answer : 3**

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