Ten gram atoms of an `alpha`-active radioisotope are disintegrating in a sealed container. In one hour the helium gas collected at STP is `11.2cm^3`. Calculate the half-life of the radioisotope.

The rate constant of a first order reaction is 2.31xx10^(-3)s^(-1) Calculate the half-life period of the activation energy of the reaction.

The V.D of a gas is 11.2 . The volume occupied by one gram of the gas at STP is

An element crystallizes into a structure which may be describes by a cubic type of unit cell having one atom on each corner of the cube and two atoms on one of its diagonals. If the volume of this unit cell is 24xx10^(-24)cm^(3) and density of element is 7.2g cm^(-3) . Calculate the number of atoms present in 200g of element.

The initial number of radioactive atoms in a radioactive sample is N_0 . If after time t the number of becomes N, then N=N_0e^(-lambdat) , where lambda is known as the decay constant of the element. The time in which the number of radioactive atoms becomes half of its initial number is called the half-life (T) of the element. The time in which the number of atoms falls to 1/e times of its initial number is the mean life (tau) of the element. The product lambdaN is the activity (A) of the radioactive sample when the number of atoms is N. The SI unit of activity is bequerel (Bq)' where 1 Bq = 1 decay. s^(-1) . The half-life of Iodine-131 is 8 d. What is the activity (in Bq) of 1 g of Iodine? (A) 2.3xx10^15 (B) 4.6xx10^15 (C) 6.9xx10^15 (D) 9.2xx10^15

A cubical box of side 1 m contains helium gas (atomic weight=4) at pressure 100 N.m^-2 During an observation time of 1s, an atom travelling with rms speed parallel to one of the edges of the cube was found to make 500 hits with a perpendicular wall without any collisions with other atoms. Evaluate the temperature of the gas

A cubical box of side 1 m contains helium gas (atomic weight=4) at pressure 100 N.m^-2 During an observation time of 1s, an atom travelling with rms speed parallel to one of the edges of the cube was found to make 500 hits with a perpendicular wall without any collisions with other atoms. Evaluate the average kinetic energy per atom.

A U-tube of uniform cross-section contains some water. When 4cm^(3) of water is poured into it, the water level rises by 1 cm in each arm of the tube. Now if 10cm^(3) of oil is poured through one of the limbs, the water level rises further by 2.2 cm in the other limb. Calculate the density of the oil.

A gaseous mixture contains 336cm^(3) of H_(2) and 224cm^(3) of He at STP. The mixture shows a pressure of 2 atm when it is kept in a container at 27^(@)C . Calculate the volume of the gas?

A cubical box of side 1 m contains helium gas (atomic weight=4) at pressure 100 N.m^-2 During an observation time of 1s, an atom travelling with rms speed parallel to one of the edges of the cube was found to make 500 hits with a perpendicular wall without any collisions with other atoms. Evaluate the total mass of the helium gas in the box.

An electronic vaccum tube is constructed and sealed at 27^@C and 1.2 times 10^-6 cm Hg pressure. The tube has a volume of 100 cm^3 . Calculate the number of gas molecules left in the tube.Avogadro number is 6.02 times 10^23 , and the gas occupies a volume of 22.4 litre at STP.