Castor oil is obtained from which of the following plants?

In a single slit diffraction experiment, the first minimum for red light $(\lambda = 660 \, nm)$ coincides with the first secondary maximum of some other wavelength $\lambda'$. The value of $\lambda'$ is ...... $\mathring{A}$.

$A$ plate of thickness $t$ made of a material of refractive index $\mu$ is placed in front of one of the slits in a double-slit experiment. What should be the minimum thickness $t$ for which the intensity at the centre of the fringe pattern is zero?

If $x$ is a solution of the equation $\sqrt{2x+1} - \sqrt{2x-1} = 1$ for $x \geq \frac{1}{2}$,then $\sqrt{4x^2-1}$ is equal to:

If $y = 4x - 5$ is tangent to the curve $y^2 = px^3 + q$ at $(2, 3)$,then

What is the concentration of nitrate ions $(NO_3^-)$ if equal volumes of $0.1 \ M \ AgNO_3$ and $0.1 \ M \ NaCl$ are mixed together (in $M$)?