In chemistry lab we perform experiments to find the unknown solution. I just want to produce some fumes in lab. We are only allowed to use few common dilute solution like $\ce{NH_4Cl}$, $\ce{NH_4OH},$ $\ce{HCl}$, and few more which are generally allowed to students. Is it possible to form fumes ...

From Chemguide: I don't understand the first equation. The chromium atoms in the dichromate ion receive 6 electrons, and their oxidation state declined from 6+ to 3+. But where do the 14 hydrogen cations get their 14 electrons in order to form water with the seven oxygens?

The melting and boiling points of transition elements increases from scandium ($1530~\mathrm{^\circ C}$) to vanadium ($1917~\mathrm{^\circ C}$). They increase because as we go across the group, we have more unpaired (free) electrons. But at chromium ($1890~\mathrm{^\circ C}$) however, the meltin...