In a $P$-type semiconductor,germanium is doped with:

The negation of the statement pattern $\sim p \vee (q \rightarrow \sim r)$ is

The basis of the quantum mechanical model of an atom is

Anthropogenic actions that lead to evolution are the use of:

If $A$ and $B$ are square matrices of order $3$, $A$ is non-singular, and $AB = O$, then $B$ is a:

When a current of $2\, A$ flows in a battery from negative to positive terminal, the potential difference across it is $12\, V$. If a current of $3\, A$ flows in the opposite direction, the potential difference across the terminals of the battery is $15\, V$. The $emf$ of the battery is ............... $V$.