Boron can be obtained by various methods but not by :

The de-Broglie wavelength of a particle moving with a velocity $2.25 \times 10^8 \ m/s$ is equal to the wavelength of a photon. The ratio of the kinetic energy of the particle to the energy of the photon is (velocity of light is $3 \times 10^8 \ m/s$). (in $/8$)

Which of the following statements is incorrect for physical adsorption?

If one end of the diameter is $(1, 1)$ and the other end lies on the line $x + y = 3$,then the locus of the centre of the circle is

$10$ cells,each of emf $E$ and internal resistance $r$,are connected in series to a variable external resistance. The figure shows the variation of the terminal potential difference of their combination with the current drawn from the combination. The emf of each cell is ............. $V$.

$\int_{-\pi / 2}^{\pi / 2} \sin |x| \, dx$ is equal to