Explanation:
1. integer (it is really simple : all positive and negative "whole" numbers).
Natural numbers are all positive whole numbers starting with 1.
Whole numbers are all positive whole numbers starting with 0 (yes, that is the only difference to Natural numbers). which is why I put "whole" under quotation marks with "integer". a negative integer number does not belong to the official set of Whole numbers. but it has the same property (no digits except 0 after the decimal point).
2.
between pi and 4.
sqrt(10) = 3.16227766...
as the closest full square number is 9 (= 3×3) and snake than 10, you know sqrt(10) has to be greater than 3 but also clearly smaller than 4 (as 4² = 16 and much larger than 10).
3.
again ?
4 7/20
as explained in the answers to the explicit question.
4.
commutative property of multiplication.
in other words : the sequence of the operands does not matter. a × b = b × a
5.
true.
as any "whole" number x can be written as x/1, yes, they are clearly a part of the rational numbers.