$BF_3$ is used as a catalyst in many industrial processes because of its .....

When radiation of wavelength $\lambda$ is incident on a metallic surface,the stopping potential is $4.8 \ V$. If the same surface is irradiated with radiation of wavelength $2\lambda$,the stopping potential is $1.6 \ V$. The threshold wavelength for the metal is:

Sulphide ores of metals are usually concentrated by froth floatation process. Which one of the following sulphide ores offers an exception and is concentrated by chemical leaching?

The compound which has one isopropyl group is:

The half-life period of a radioactive element $X$ is the same as the mean life time of another radioactive element $Y$. Initially,they have the same number of atoms. Then:

Which of the following ray diagrams shows physically possible refraction?