21. A biconvex lens has a focal length 2/3 times the radius of curvature of either surface. The refractive index of lens is:

(a) 1.55
(b) 1.65
(c) 1.75
(d) 1.85

Answer: (c)

22. An audio signal of amplitude 0.1 V is used in amplitude modulation of a carrier wave of amplitude 0.2 V. The modulation index is:
(a) 0.1
(b) 0.3
(c) 0.5
(d) 0.7

Answer: (c)

23. Consider the following:
1. Byte
2. Double
3. Long
4. Short

Which of the above are the valid integer types of JAVA ?
(a) 1, 2 and 3 only
(b) 1, 2 and 4 only
(c) 2, 3 and 4 only
(d) 1, 3 and 4 only

Answer: (d)

24. In JAVA, the math class has a powerful method, which generates a random value:
(a) Greater than or equal to 0.0 and less than 1.0
(b) Greater than or equal to 0.0 and less than or equal to 1.0
(c) Greater than 1.0
(d) Less than or equal to 1.0

Answer: (a)

25. In JAVA , ‘‘Welcome’’. replace First (“e”, “AB”) returns a new string:
(a) WABlcomAB
(b) WABlcome
(c) Welcome
(d) WABLCOME

Answer: (b)

26. An object whose contents cannot be changed once the object is created is called:
(a) Immutable object
(b) Mutable object
(c) Smart object
(d) Rich object

Answer: (a)

27. Which one of the following fundamental features of the OOPs is not supported by 𝐶𝐶++?
(a) Persistence
(b) Delegation
(c) Genericity
(d) Data abstraction

Answer: (a)

28. Which one of the following features is supported by 𝐶𝐶++ but not by JAVA ?
(a) Encapsulation
(b) Multiple inheritance
(c) Concurrency
(d) Garbage collection

Answer: (b)

29. Consider the following statements regarding JAVA :
1. It is a high performance programming language
2. It does not support pointers
3. It omits features that make 𝐶𝐶++ complex
4. It provides platform-dependent solution

Which of the above statements are correct?
(a) 1, 2 and 4 only
(b) 1, 3 and 4 only
(c) 1, 2 and 3 only
(d) 2, 3 and 4 only

Answer: (c)

30. Consider the following features regarding 𝐶𝐶++:
1. Emphasis on algorithm rather than data
2. Improvement over the structural programming paradigm
3. Relationship can be created between similar, yet distinct data types

Which of the above features are correct?
(a) 2 and 3 only
(b) 1 and 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Answer: (a)