Sodium and copper have work functions of $2.3 \ eV$ and $4.5 \ eV$ respectively. The ratio of their threshold wavelengths is nearest to:

True coelom appeared first in the course of evolution in

$A$ capacitor is charged by using a battery,which is then disconnected. $A$ dielectric slab is then inserted between the plates. What is the result?

Consider two statements $S_1$ and $S_2$. $S_1$: If $f(x)$ is a differentiable function with $f^{\prime}(x) = 0$ in $(a, b)$ and $f(x)$ is increasing in $(a, b)$,then $\frac{f(x)}{f^{\prime}(x)}$ is also increasing in $(a, b)$. $S_2$: Both $\sin x$ and $\tan x$ are increasing functions in $\left(0, \frac{\pi}{2}\right)$. Which of the following is true?

$A$ light string passing over a smooth light pulley connects two blocks of masses $m_1$ and $m_2$ (vertically). If the acceleration of the system is $\frac{g}{8}$,then the ratio of the masses is

Which type of drug is obtained from opium?