Which one of the following gives Prussian blue colour?

Which one of the following elements on doping with germanium,makes it a $p$-type semiconductor?

Twelve cells,each having emf $E$ volts,are connected in series and are kept in a closed box. Some of these cells are wrongly connected with positive and negative terminals reversed. This $12$-cell battery is connected in series with an ammeter,an external resistance $R$ ohms,and a two-cell battery (two cells of the same type used earlier,connected perfectly in series). The current in the circuit when the $12$-cell battery and $2$-cell battery aid each other is $3 \text{ A}$,and it is $2 \text{ A}$ when they oppose each other. Then,the number of cells in the $12$-cell battery that are connected wrongly is:

According to the Neo-Darwinian theory,which of the following is responsible for the origin of new species?

At a certain temperature,the equilibrium constant $K_c$ is $0.25$ for the reaction:
$A_{2(g)} + B_{2(g)} \rightleftharpoons C_{2(g)} + D_{2(g)}$
If we take $1 \ mol$ of each of the four gases in a $10 \ L$ container,what would be the equilibrium concentration of $A_{2(g)}$ (in $M$)?

If $A$ is the areal velocity of a planet of mass $M$,its angular momentum is