Magnifying power of a simple microscope is (when final image is formed at $D = 25 \ cm$ from eye)

If $\tan ^{-1} a+\tan ^{-1} b+\tan ^{-1} c=\pi$,then which of the following statements is true?

Which of the following statements is incorrect for $B_{2}H_{6}$?

At a certain place,the angle of dip is $60^{\circ}$ and the horizontal component of the earth's magnetic field $(B_H)$ is $0.8 \times 10^{-4} ~T$. The earth's overall magnetic field is

Heat is supplied to a diatomic gas at constant pressure. The ratio of $\Delta Q : \Delta U : \Delta W$ is

If $I_n = \int x^n \cdot e^{cx} \, dx$ for $n \geq 1$,then $c \cdot I_n + n \cdot I_{n-1}$ is equal to