An ideal refrigerator has a freezer at a temperature of $-13^{\circ}C$. The coefficient of performance of the refrigerator is $5$. The temperature of the air (to which heat is rejected) will be:

The wavelength of ${K_\alpha }$ $X-$rays produced by an $X-$ray tube is $0.76 \ \mathring A$. The atomic number of the anode material of the tube is:

Why are modern techniques implemented in fisheries?

When the angle of inclination of an inclined plane is $\theta$, an object slides down with uniform velocity. If the same object is pushed up with an initial velocity $u$ on the same inclined plane, it goes up the plane and stops at a certain distance on the plane. Thereafter, the body:

Which of the following is not a broad spectrum antibiotic?

If $P = \begin{bmatrix} 1 & \alpha & 3 \\ 1 & 3 & 3 \\ 2 & 4 & 4 \end{bmatrix}$ is the adjoint of a $3 \times 3$ matrix $A$ and $|A| = 4$,then $\alpha$ is equal to