Match List - I with List - II. List - I (a) 10 km height over earth's surface (b) 70 km height over earth's surface (c) 180 km height over earth's surface (d) 270 km height over earth's surface List - II (i) Thermosphere (ii) Mesosphere (iii) Stratosphere (iv) Troposphere

What should be the height of transmitting antenna and the population covered if the television telecast is to cover a radius of 150 km? The average population density around the tower is 2000/km2 and the value of Re = 6.5 $$\times$$ 106 m.

In amplitude modulation, the message signal Vm(t) = 10 sin (2$$\pi$$ $$\times$$ 105t) volts and Carrier signal VC(t) = 20 sin(2$$\pi$$ $$\times$$ 107 t) volts The modulated signal now contains the message signal with lower side band and upper side band frequency, therefore the bandwidth of modulated signal is $$\alpha$$ kHz. The value of $$\alpha$$ is :

A transmitting antenna at top of a tower has a height of 50 m and the height of receiving antenna is 80 m. What is range of communication for Line of Sight (LoS) mode? [use radius of earth = 6400 km]

An antenna is mounted on a 400 m tall building. What will be the wavelength of signal that can be radiated effectively by the transmission tower upto a range of 44 km?

In the given figure, the energy levels of hydrogen atom have been shown along with some transitions marked A, B, C, D and E. The transitions A, B and C respectively represent :

According to Bohr atomic model, in which of the following transitions will the frequency be maximum?

Two radioactive substances X and Y originally have N1 and N2 nuclei respectively. Half life of X is half of the half life of Y. After three half lives of Y, number of nuclei of both are equal. The ratio {{{N_1}} \over {{N_2}}} will be equal to :

The wavelength of the photon emitted by a hydrogen atom when an electron makes a transition from n = 2 to n = 1 state is :

If $$\lambda$$1 and $$\lambda$$2 are the wavelengths of the third member of Lyman and first member of the Paschen series respectively, then the value of $$\lambda$$1 : $$\lambda$$2 is :

A radioactive sample is undergoing $$\alpha$$ decay. At any time t1, its activity is A and another time t2, the activity is {A \over 5}. What is the average life time for the sample?

Calculate the time interval between 33% decay and 67% decay if half-life of a substance is 20 minutes.

The half-life of Au198 is 2.7 days. The activity of 1.50 mg of Au198 if its atomic weight is 198 g mol$$-$$1 is, (Na = 6 $$\times$$ 1023/mol).

If an electron is moving in the nth orbit of the hydrogen atom, then its velocity (vn) for the nth orbit is given as :

Which level of the single ionized carbon has the same energy as the ground state energy of hydrogen atom?

The atomic hydrogen emits a line spectrum consisting of various series. Which series of hydrogen atomic spectra is lying in the visible region?

Imagine that the electron in a hydrogen atom is replaced by a muon ($$\mu$$). The mass of muon particle is 207 times that of an electron and charge is equal to the charge of an electron. The ionization potential of this hydrogen atom will be :

A radioactive sample disintegrates via two independent decay processes having half lives $$T_{1/2}^{(1)}$$ and $$T_{1/2}^{(2)}$$ respectively. The effective half-life T1/2 of the nuclei is :

The decay of a proton to neutron is :

A radioactive material decays by simultaneous emissions of two particles with half lives of 1400 years and 700 years respectively. What will be the time after which one third of the material remains ? (Take ln 3 = 1.1)