Radon is a radioactive gas with half-life 56 s.For health reasons,the maximum permissible level of radon in air in a building is set a t 1 radon atom for every `.15xx10^(21)` molecules of air 1 mol of air in the building is contained in 0.024 `m^3`.Calculate ,for this building
the maximum permissible number of radon atom in `1.0 m^3` of air

Radon is a radioactive gas with half-life 56 s.For health reasons,the maximum permissible level of radon in air in a building is set a t 1 radon atom for every .15xx10^(21) molecules of air 1 mol of air in the building is contained in 0.024 m^3 .Calculate ,for this building the number of molecules for air in 1.0 m^3 .

Light travels from air to water of refractive index 1.33. calculate the speed of light in water, if speed of light in air is 3.0xx10^8 m/s

Velocity of light in a liquid is 1.5 xx 10^8 ms^(-1) and in air,it is 3xx10^8 m s^(-1) .If a ray of light passes from this liquid to air ,calculate the value of critical angle.

Two equal charges placed in air separated by a distance 3 m repel each other with force 0.1 g f. Calculate the magnitude of either of the charges.

A small retangular coil ABCD contains 140 turns of wire. The sides AB and BC of the coil are of length 4.5 and 2.8 cm respectively, as shown in the figure The coil is held between the poles of a large magnet so that the coil can rotate about an axis thorugh its centre. The magnet produces a uniform magnetic field of flux density B between its poles. When the current in the coil is 170 mA, the maximum torque produced in the coil is 2.1 xx 10^-3 N m . The current in the coil in (a) is switched off and the coil s positioned as shown in the figure. The coil is then turned thorugh an angle of 90^@ in a time of 0.14 s. Calculate the average e.m.f. induced in the coil.

A small retangular coil ABCD contains 140 turns of wire. The sides AB and BC of the coil are of length 4.5 and 2.8 cm respectively, as shown in the figure The coil is held between the poles of a large magnet so that the coil can rotate about an axis thorugh its centre. The magnet produces a uniform magnetic field of flux density B between its poles. When the current in the coil is 170 mA, the maximum torque produced in the coil is 2.1 xx 10^-3 N m . For the coil in the position shown in the figure. calculate the magnitude of the force on (i) side AB of the coil and (ii) side BC of the coil.

A paramagnetic gas consists of atoms each with a dipole moment of 1.5 xx 10^-23 j T^-1 . The temperature of the gas is 27^@C and its number density is 2xx10^26 m^-3 . What is the maximum magnetisation of the sample possible, when it is placed in an external magnetic field?

Velocity of light in glass in 2 xx 10^8 m s^(-1) and that in air is 3 xx 10^8 m s^(-1) .By how much would an ink dot appear to be raised,when covered by a glass plate 6.0 cm thick?

Air entering the lungs ends up in tiny sacs called alveoli.From the alveoli, the oxygen diffuses into the blood. The average radius of the alveoli is 0.0050 cm and the air inside contains 14 per cent oxygen. Assuming that the pressure in the alveoli is 1.0 atm and the temperature is 37^(@)C , calculate the number of oxygen molecules in one of the alveoli.