If a centimolal aqueous solution of K$$_3$$[Fe(CN)$$_6$$] has degree of dissociation 0.78. What is the value of van't Hoff factor?

Which among the following is antioxident?

In a triangle $$A B C$$ with usual notations, if $$\frac{\cos A}{a}=\frac{\cos B}{b}=\frac{\cos C}{c}$$, then area of triangle $$A B C$$ with $$a=\sqrt{6}$$ is

If $$\frac{x}{\sqrt{1+x}}+\frac{y}{\sqrt{1+y}}=0, x \neq y$$, then $$(1+x)^2 \frac{d y}{d x}=$$