Define :- percentage by mass.

Define pleura.

Define : Moderator.

Define : Vibration

Define: Centre of mass

Define centre of mass.

Define atomic mass. Chlorine has two stable isotopes , Cl-35 and Cl-37 with atomic masses 34.968u and 36.956u respectively . If the average atomic mass is 35.453u , calculate the percentage abundance.

Calculate the mass percentage composition of the elements in nitric acid (H=1 ,N=14, O=16) .

A compound on analysis gave the following percentage composition by mass: H = 9.09, O = 36.36, C = 54.55. Molecular mass of compound is 88. Find its molecular formula.

Uranium. has two isotopes of masses 235 and 238 units. If both of them are present in Uranium hexafluoride gas, find the percentage ratio of difference in rms velocities of two isotopes to the rms velocity of heavier isotope.

Define mass defect.