For a first order reaction, (A) $$\to$$ products, the concentration of A changes from 0.1 M to 0.025 M in 40 minutes. The rate of reaction when the concentration of A is 0.01 M is :

In which of the following pairs the two species are not isostructural ?

Ortho–Nitrophenol is less soluble in water than p– and m– Nitrophenols because :

The increasing order of the ionic radii of the given isoelectronic species is :