Which of the following alkaline earth metal nitrides is volatile?

$A$ semiconductor $X$ is made by doping a germanium crystal with arsenic $(Z=33)$. $A$ second semiconductor $Y$ is made by doping germanium with indium $(Z=49)$. The two are joined end to end and connected to a battery as shown. Which of the following statements is correct?

Leaching of $Ag_2S$ is carried out by heating it with a dilute solution of

Which alga exhibits a haplo-diplontic life cycle?

Wavelengths of light used in an optical instrument are $\lambda_1 = 4000 \ Å$ and $\lambda_2 = 5000 \ Å$. The ratio of their respective resolving powers (corresponding to $\lambda_1$ and $\lambda_2$) is:

Which one of the following has the longest covalent bond distance?