The five-kingdom classification system was proposed by whom?

$2 \tanh^{-1} \frac{1}{2}$ is equal to

$A$ hyperbola passes through a focus of the ellipse $\frac{x^2}{169} + \frac{y^2}{25} = 1$. Its transverse and conjugate axes coincide respectively with the major and minor axes of the ellipse. The product of their eccentricities is $1$. Then,the equation of the hyperbola is:

Which of the following is the correct electronic configuration of $Cr$ $(Z = 24)$?

Which of the following radioisotopes is used as anticancerous?

The de-Broglie wavelength of a particle moving with a velocity of $2.25 \times 10^8 \ m/s$ is equal to the wavelength of a photon. The ratio of the kinetic energy of the particle to the kinetic energy of the photon is: (in $/8$)