The de-Broglie's wavelength of electron present in first Bohr orbit of 'H' atom is :

In KO₂, the nature of oxygen species and the oxydation state of oxygen atom are, respectively :

Which of the following best describes the diagram below of a molecular orbital ?

Let f(x) be a polynomial of degree $$4$$ having extreme values at $$x = 1$$ and $$x = 2.$$

If   $$\mathop {lim}\limits_{x \to 0} \left( {{{f\left( x \right)} \over {{x^2}}} + 1} \right) = 3$$   then f($$-$$1) is equal to :