How many stereoisomers are possible for the following molecule?

Which one of the following elements reduces $NaOH$ to $Na$?

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

The expression $1+x \log _e a+\frac{x^2}{2 !}(\log _e a)^2+\frac{x^3}{3 !}(\log _e a)^3+\ldots$ for $a>0, x \in R$ is equal to:

Who proposed the theory that "Cells arise only from the pre-existing cells"?

$A$ double slit experiment is performed by using light of wavelength $6000\,\mathring{A}$. If the distance of the screen is $1\,m$ and the slits are $0.1\,cm$ apart,then calculate the angular position of the $10^{th}$ bright fringe.