Class 12th

A $100\mathrm{e}\mathrm{V}$ electron collides with a stationary helium ion ${\mathrm{H}\mathrm{e}}^{+}$ in its ground state and excites it into higher energy level $n$ . After collision ${\mathrm{H}\mathrm{e}}^{+}$ ions emits two photons in succession with a wavelength $1085\text{?}$ and $304\text{?}$  to reach its ground state. Quantum number of excited state $n$  is

Which of the following is correct:

Correct acidic strength order of the given carbonyl compound is

A double convex lens is made of glass which has its refractive index of 1.55 for violet rays and 1.50 for red rays. If the focal length for violet rays is 20cm, then the focal length for red rays will be cm.

A beam of unpolarized light of intensity I? is incident on a polaroid A. Then it is passed through another polaroid B. If the intensity of the emergent light is 18% of the original unpolarized light then find the angle (nearest integer in degree) between the principal plane of polaroid A and B.

In the given circuit find the current through the Zener diode in mA.

Incorrect statement among the following is:

An inductor of inductance 0.1H and a resistor of resistance 8Ω are connected in series to a battery of emf 1.5 V through a switch. Find the initial rate of growth of current when the switch is closed (in A/s).

A capacitor of capacitance 3µF is charged to a potential difference of 12V. Another identical capacitor, initially uncharged is filled with a dielectric having dielectric constant K and it is connected to the charged capacitor. The final common potential difference across both capacitors is found to be 2V. Find the value of k.

In a young's double slit experiment with monochromatic light, fringes are obtained on a screen placed at some distance from the slits. If the screen is moved 8 cm towards the slits, the change in fringe width is 4 * 10^-5 m. If the separation between the slits is 1 mm, find the wavelength of light used (in nm ).