Seven white balls and three black balls are randomly arranged in a row. The probability that no two black balls are placed adjacently is

Two photons of energies twice and thrice the work function of a metal are incident on the metal surface. Then,the ratio of maximum velocities of the photoelectrons emitted in the two cases respectively,is

From which part is clove oil extracted?

Which of the following magnetic properties is exhibited by the compounds of alkaline earth metals?

Water from a tap emerges vertically downwards with initial velocity $4 ~m/s$. The cross-sectional area of the tap is $A$. The flow is steady and pressure is constant throughout the stream of water. The distance $h$ vertically below the tap, where the cross-sectional area of the stream becomes $\frac{2}{3} A$, is $(g=10 ~m/s^2)$ (in $~m$)

$Saccharomyces\, cerevisiae$ is used in the production of......