Person is referred to as a class or a type, while p1 is referred to as an object or an instance.

(i) A class defines a data abstraction by grouping related data items. A class is not just data, it has functions defined within it.
(ii) Functions are subordinate to the class because their job is to do things with the data of the class.

rational(n, d):
return [n, d]
numer(x):
return x[0]
denom(x):
return x[1]

(i) Selector
(ii) Constructor

(i) There can be different ways to implement an ADT, for example, the, List ADT can be implemented using singly linked list or doubly linked list.
(ii) Similarly, stack ADT and Queue ADT can be implemented using lists

(i) A tuple is a comma-separated sequence of values surrounded with parentheses. Tuple is similar to a list.
(ii) The difference between the two is that you cannot change the elements of a tuple once it is assigned whereas in a list, elements can be changed
(iii) Example : colour = ('red', 'blue, 'Green')

List is constructed by placing expressions within square brackets separated by commas. List can store multiple values.
Example:
1st := [10, 20]
x, y:= 1st
In the above example x will become 10 and y will become 20.

(i) Any way of bundling two values together into one can be considered as a Pair. Lists are a common method to do so. Therefore List can be called as Pairs.
(ii) Example: List = [10,20,30]

S.No	Constructors	Selectors
(i)	Constructors are functions that build the abstract data type.	Selectors are functions that retrieve information from the data type.
(ii)	Constructors create an object, bundling together different pieces of information.	Selectors extract individual pieces of information from the object

 

(i) Abstract Data type (ADT) is a type (or class) for objects whose behavior is defined by a set of value and a set of operations. 
(ii) The definition of ADT only mentions what operations are to be performed but not how these operations will be implemented.