Class 12th

A beam of monochromatic light is used to excite the electron in Li⁺⁺ from the first orbit to the third orbit. The wavelength of monochromatic light found to be x * 10^-10m. The value of x is_________.

[Given hc = 1242 eV nm]

In Young's double slit experiment the two slits are 0.6mm distance apart. Interference pattern is observed on a screen at a distance 80cm from the slits. The first dark fringe is observed on the screen directly opposite to one of the slits. The wavelength of light will be__________nm.

Among the statements $(a-d)$ , the incorrect ones are:

Octahedral $\mathrm{C}\mathrm{o}$ (III) complexes with strong field ligands have very high magnetic moments

When ${\mathrm{\Delta }}_0<\mathrm{P}$ , the d-electron configuration of $\mathrm{C}\mathrm{o}$ (III) in an octahedral complex is ${\mathrm{t}}_{\mathrm{e}\mathrm{g}}^4{\mathrm{e}}_{\mathrm{g}}^2$
Wavelength of light absorbed by ${\left[\mathrm{C}\mathrm{o}(\mathrm{e}\mathrm{n}{)}_3\right]}^{3+}$ is lower than that of ${\left[{\mathrm{C}\mathrm{o}\mathrm{F}}_6\right]}^{3-}$

If the ${\mathrm{\Delta }}_0$ for an octahedral complex of $\mathrm{C}\mathrm{o}$ (III) is $\mathrm{18,000}{\mathrm{c}\mathrm{m}}^{-1}$ , the ${\mathrm{\Delta }}_{\mathrm{t}}$ for its tetrahedral complex with the same ligand will be $\mathrm{16,000}{\mathrm{c}\mathrm{m}}^{-1}$

A 220 V, 50 Hz AC source is connected to a 25 V, 5 W lamp and an additional resistance R in series (as shown in figure)

to run the lamp at its peak brightness, then the value of R (in ohm) will be__________.

For the following reactions:

${\mathrm{k}}_{\mathrm{s}}$ and ${\mathrm{k}}_{\mathrm{e}}$ are respectively, the rate constant for substitution and elimination, and $\mu =\frac{{\mathrm{k}}_{\mathrm{s}}}{{\mathrm{k}}_{\mathrm{e}}}$ , the correct option is

Identify the correct Logic Gate for the following output (Y) of two inputs A and B.

A hydrogen atom in its ground state absorbs 10.2 eV of energy. The angular momentum of electron of the hydrogen atom will increase by the value of: 

(Given, Planck's constant  = 6.6 * 10^-34 Js).

Consider a light ray travelling in air is incident into a medium of refractive index $\sqrt[]{2n}.$  The incident angle is twice that of refracting angle. Then, the angle of incidence will be:

In the following reaction sequence, structures of $A$ and $B$ respectively will be

An observer moves towards stationary source of sound with a velocity equal to one-fifth of the velocity of sound. The percentage change in the frequency will be: