Saponification is

$A$ circular disc of radius $R$ is removed from a bigger circular disc of radius $2R$ such that the circumferences of the discs touch. The centre of mass of the new disc is at a distance $\alpha R$ from the centre of the bigger disc. The value of $\alpha$ is

Consider the set of all triangles $OPQ$ where $O$ is the origin and $P$,$Q$ are distinct points in the plane with non-negative integral coordinates $(x, y)$ such that $5x + y = 99$. The number of such distinct triangles whose area is a positive integer is:

In maize,hybrid vigour is exploited by

The speed of an electron having a wavelength of $10^{-10} \ m$ is ........... $\times 10^6 \ m/s$.

Which of the following hydrides has the lowest boiling point?