Page 52 - ComputerScience_Class_11

F. Case study-based questions.

Raghav, a 16-year-old student, had set his date of birth (DOB) as the password for his computer, but when his parents tried to
access the system, they couldn't figure it out. Confused, they asked Raghav how he had created the password and he explained
that he had converted his DOB into another number system. Instead of using the common decimal system, Raghav had converted
his DOB into binary. His birth date was 03/12/2006. He first converted the day (03) into binary as 00000011, the month (12) as
00001100 and the year (2006) as 11111010110. His final password was the concatenation of these binary numbers: 00000011
00001100 11111010110. This simple act of converting his DOB into a different number system made it difficult for anyone to
guess the password. The binary system, using only 0s and 1s, is foundational in computing and using it for a password adds a layer
of security. This case demonstrates how converting even basic information, like a birth date, into a different number system can
enhance password security, making it much harder for others to crack.
Based on the given case, answer the following questions:
1. What was Raghav's password for his computer?
Ans. Raghav's password was the binary form of his date of birth: 00000011 00001100 11111010110.
2. Which number system did Raghav use to convert his date of birth for the password?
Ans. Raghav used the binary number system.
3. Could Raghav have used a different number system to make his password even stronger? If yes, which one could he have used?
Ans. Yes, Raghav could have used other number systems like hexadecimal or octal to make his password even more complex.
4. Why is converting a password into a different number system considered a good security practice?
Ans. Converting a password into a different number system adds a layer of complexity, making it harder for someone to guess the
password using simple methods.

Unsolved Questions

A. Tick ( ) the correct option.

1. Which of these is the base of an octal number system?
a. 2 b. 8
c. 16 d. 10
2. Identify the binary equivalent of the decimal number 9.
a. 1000 b. 1010
c. 1001 d. 1011
3. Which of the following is not an octal number?
a. 827 b. 567
c. 777 d. 245.27
4. To express a hexadecimal number to its binary equivalent, each hexadecimal digit is expressed into ………………… .
a. 2 bits form b. 3 bits form
c. 4 bits form d. 15 bits form
5. The octal equivalent of decimal number 10 is ………………… .
a. 1010 b. A
c. 0010 d. 12

6. Adding binary digits 1+1+1 will result in ………………….
a. Sum 1, Carry 0 b. Sum 0, Carry 1
c. Sum 3, Carry 0 d. Sum 1, Carry 1
7. Adding octal digits 6+7 will result in ………………… .
a. Sum 13, Carry 0 b. Sum 5, Carry 1
c. Sum 1, Carry 5 d. Sum 7, Carry 1

8. 15’s complement of hexadecimal number AB51 is ………………… .
a. 54AE b. 55AF
c. 65BF d. 65BE

50 Touchpad Computer Science (Ver. 3.0)-XI