The mean life of an elementary particle pion is `2xx10^(-7)` ns. The age of the univers is about `4xx10^9` years. Identify a physically meaning time that is approximately half way between these two on a logarithmic scale.

The radius of a proton is about 10^(-9) micron and the radius of universe is about 10^(28) cm. Name a physical object whose size is approximately halfl way between these two extermes on a logarithmin scale.

The compressibility of water is 46.4 xx 10^(-6)//atm . This means that

The half life of radioactive substance is 1.1xx10^7 s. What is the decay rate for 4.4xx10^15 atoms of the substance ?

In the chemical analysis of a rock the mass ratio of two radioactive isotopes is found to be 100:1 . The mean lives of the two isotopes are 4xx10^9 years and 2xx10^9 years, respectively. If it is assumed that at the time of formation the atoms of both the isotopes were in equal propotional, calculate the age of the rock. Ratio of the atomic weights of the two isotopes is 1.02:1 .

Age of A is 1.5 times of B. The ratio of their ages after 10 years is 4 : 3. then what is the current age of B?

The decay constant of a radioactive material is 5 xx 10^(-4) per year.find its half-life period.

The half-life of a radioactive substance against alpha- decay is 1.2 xx 10^7 s . What is the decay rate for 4 xx 10^15 atoms of the substance ?

The half - life of ._6C^(14) , if its lamda is 2.31 xx10^(-4) " year"^(-1) is