Set of rational numbers is not hold which of the following with respect to closure property ? 

Correct option is (C) \(\frac{a+b}{2}\) Rational number between a and b is \(\frac{a+b}{2}.\)

Correct option is (D) \(\frac{a+b}{2}\) \(\frac{a+b}{2}\) is a rational number lying between two rational numbers a and b.

Correct option is (D) 35/38 Let the second number be x. \(\therefore\) x + \((\frac{-8}{19})\) = \(\frac{1}{2}\) \(\Rightarrow\) x = \(\frac{1}{2}\) - \((\frac{-8}{19})\) = \(\frac{1}{2}\) + \(\frac{8}{19}\) \(=\frac{19+8\times2}{38}\) \(=\frac{19+16}{38}\) \(=\frac{35}{38}.\)

Correct Answer - `f^(-1):Q to Q , f^(-1)(y)=(y+4)/(5)`

Correct Answer - (ii),(iv),(v) are commutative (v) is associative (v) has identify element

A number which can neither be expressed as a terminating decimal nor as a repeating decimal is called an irrational number. For example,  0.33033003300033…  On the other hand, every rational number is expressible...

Correct Answer - D