21. Does the minimum spanning tree of a graph give the shortest distance between any 2 specified nodes?
Ans: No.
Minimal spanning tree assures that the total weight of the tree is kept at its minimum. But it doesn’t mean that the distance between any two nodes involved in the minimum-spanning tree is minimum.

22. Define double linked list?
Ans: It is a collection of data elements called nodes, where each node is divided into three parts
i) An info field that contains the information stored in the node
ii) Left field that contain pointer to node on left side
iii) Right field that contain pointer to node on right side

23. What are the goals of Data Structure?

Ans: It must rich enough in structure to reflect the actual relationship of data in real world. The structure should be simple enough for efficient processing of data.

24. Calculate the efficiency of sequential search?
Ans: The number of comparisons depends on where the record with the argument key appears in the table
If it appears at first position then one comparison
If it appears at last position then n comparisons
Average=(n+1)/2 comparisons
Unsuccessful search n comparisons
Number of comparisons in any case is O (n).

25. What are the disadvantages of circular list?
Ans:
i) We can’t traverse the list backward
ii) If a pointer to a node is given we cannot delete the node

26. Is any implicit arguments are passed to a function when it is called?
Ans: Yes there is a set of implicit arguments that contain information necessary for the function to execute and return correctly. One of them is return address which is stored within the function’s data area, at the time of returning to calling program the address is retrieved and the function branches to that location.

27. List out the areas in which data structures are applied extensively?
Ans: 
Compiler Design,
Operating System,
Database Management System,
Statistical analysis package,
Numerical Analysis,
Graphics,
Artificial Intelligence,
Simula

28. What are the issues that hamper the efficiency in sorting a file?
Ans: The issues are
i) Length of time required by the programmer in coding a particular sorting program
ii) Amount of machine time necessary for running the particular program
iii) the amount of space necessary for the particular program.

29. If you are using C language to implement the heterogeneous linked list, what pointer type will you use?
Ans: The heterogeneous linked list contains different data types in its nodes and we need a link, pointer to connect them. It is not possible to use ordinary pointers for this. So we go for void pointer. Void pointer is capable of storing pointer to any type as it is a generic pointer type.

30. What is a spanning Tree?
Ans: A spanning tree is a tree associated with a network. All the nodes of the graph appear on the tree once. A minimum spanning tree is a spanning tree organized so that the total edge weight between nodes is minimized.