Check whether the following sentences are statements. Give reasons for your answer.
(i) The earth is a planet.
(ii) There are 35 days in a month.
(iii) Mathematics is difficult.
(iv) Every square is a rectangle.
(v) Every set is a finite set.
(vi) Every real number is a complex number.
(vii) 9 is less than 7.
(viii) The square of a natural number is an even number.

Explanation

(i) It is a scientifically established fact that the earth is a planet.
So, the given sentence is true.
Hence, it is a statement.
(ii) We know that the maximum number of days in a given month is
31. So, the given sentence is false.
Therefore, it is a statement.
(iii) For some people mathematics can be easy and for some others it can be difficult.
So, we cannot judge whether the given sentence is true or false.
Hence, it is not a statement.
(iv) In a square, every angle measures `90^(@)` and its opposite sides are equal.
So, it is a rectangle.
Thus, the given sentence is true.
Hence, it is a statement.
(v) Since there are sets which are not finite, so the given sentence is false.
Therefore, it is a statement.
(vi) Every real number a can be written as a= (a+ 0i).
So, every real number is a complex number.
Therefore, the given sentence is true.
Hence, it is a statement.
(vii) Since 9 is greater than 7, so the given sentence is false.
Hence, it is a statement.
(viii) We know that 2 and 3 are natural numbers such that `2^(2) = 4,`
which is even and `3^(2) = 9,` which is odd.
So, the given sentence is sometimes true and sometimes false.
Therefore, it is not a statement.