The number of $5$-digit numbers that are not divisible by $5$ and consist of different odd digits is:

What is the total number of orbitals associated with the principal quantum number $n=3$?

Two thick wires and two thin wires,all of the same material and same length,form a square in three different ways $P$,$Q$,and $R$ as shown in the figure. With the current connection shown,the magnetic field at the centre of the square is zero in which cases?

As the switch $S$ is closed in the circuit shown in the figure,the current passing through it is ................ $A$.

An auditorium has a volume of $10^5 \ m^3$ and a total absorption area of $2 \times 10^4 \ m^2$. Its average absorption coefficient is $0.2$. The reverberation time of the auditorium in seconds is:

The electronic configuration of the phosphide ion $(P^{3-})$ is similar to that of: