Which phylum is characterized by the presence of a central cavity known as the spongocoel?

The component of vector $\overrightarrow{A} = a_x \hat{i} + a_y \hat{j} + a_z \hat{k}$ along the direction of $\hat{i} - \hat{j}$ is

Two point charges $+8q$ and $-2q$ are located at $x = 0$ and $x = L$ respectively. The location of a point on the $x$-axis at which the net electric field due to these two point charges is zero is

Vertebral column is derived from

If the internal energy of an ideal gas decreases by the same amount as the work done by the system,the process is

$A$ thin flexible wire of length $L$ is connected to two adjacent fixed points and carries a current $I$ in the clockwise direction as shown. When the system is placed in a uniform magnetic field of strength $B$ directed into the plane of the paper,the wire takes the shape of a circle. The tension in the wire after acquiring the circular shape is