Class 12th

For an endothermic reaction, energy of activation is E_a and enthalpy of reaction is ?H (both of these in kJ/mol). Minimum value of E_a will be

The area of cross-section of cylindrical wire increases uniformly from left to right as shown in figure. When steady current flows in the wire, then in the direction of current

The current in a coil changes from 8 A to zero in 0.2 s. If self-inductance is 4 H then average induced emf is:

In Bohr's model of hydrogen atom, which of the following represents the variation of nth orbit radius with n?

An objective lens of a telescope has diameter 200 cm. The limit of resolution of telescope for wavelength 600 nm is nearly

A radioactive element undergoes successive radioactive decay and decays into The number of a and b– particles emitted respectively are:

The logic gate realised from the circuit as shown in figure is (P and Q are inputs and Z is output)

Maximum wavelength in Balmer series of hydrogen spectrum is (R : Rydberg constant)

The B-H curve of two material are given below. Substance (a) most likely indicate