An electric bulb of volume 250 c.c was sealed off at a pressure of `10^(-3)` mm of Hg and at `27^@C` . Calculate the number of air molecules now present in the bulb . Avogadro's number = `6 xx 10^23// gm` mol.

Calculate the volume of 4 gm molecule of hydrogen at 27^@C and 750 mm pressure.

Quantum Nature of Charge In Milikan's oil drop experiment , the charge present on an oil drop is 12.8 xx 10^(-18)C, Calculate the number of electrons presents in oil drop.

What is the number of molecules in a container of volume 5 m^3 at a pressure of 2xx10^(-5) N/m^2 and at a temperature of 300 K ? Take k_B = 1.4 xx 10^(-23) J/K.

Copper crystallises with face centred cubic unit cell. If the radius of copper atom is 127.8 pm, calculate the density of copper metal. (Atomic mass of Cu= 63.55 u and Avogadro's number, N_(A)=6.02xx10^(23)"mol"^(-1) )

Calculate the number of molecules in one cc of a perfect gas at 27^@C and at a pressure of 15 mm of mercury. Take mean KE of a molecule at 27^@C as 5xx10^(-11) J and density of mercury = 13600 kg/m^3 and g= 9.8 m/s^2 .

96500 coulomb charge deposits 108 gm silver considering the charge of one electron is 1.6xx10^-19C , find the value of Avogadro's number

From the value of a Faraday ( 96500 C ) and Avogadro number ( 6.023 xx 10^(23) ) , calculate the coulomb charge on an electron.

Twenty per cent of the surface sites of a catalyst is occupied by nitrogen molecules. The density of surface sites is 6.023 xx 10^(14) g cm^(-3) . The total surface area is 1000 cm^2 . The catalyst is heated to 300 K and nitrogen is completely adsorbed into a pressure of 0.001 atm and volume of 2.46 cmo. Calculate the number of sites occupied by nitrogen molecules.