Two identical samples (same material and same amout) P and Q of a radioactive substance having mean life T are observed to have activities `A_P` and `A_Q` respectively at the time of observation. If P is older than Q, then the difference in their age is

Two radioactive substances P and Q have half-life 6 months and 3 months respectively. Find the ratio of the activity of these two materials after one year.

The ratio between the present ages of P and Q is 3 : 4 respectively. Four years hence Q will be five years older than P. What is P's present age?

Two identical wires of substances 'P' and 'Q' are subjected to equal stretching force along the length. If the elongation of 'Q' is more than that of 'P', then

Two identical wires of substances 'P' and 'Q' are subjected to equal stretching force along the length. If the elongation of 'Q' is more than that of 'P', then

Two metalic spheres p and Q are made of same material have same smoothness but the weight of p is 8 times that of Q if the two are heated to same temperature and left to cool then the ratio of rate of cooling of Q to that of p is

Let p be the mean of m observations and q be the mean of n observations, where p lt q . If the combined mean of (m + n) observations is c, then which one of the following is correct?

The sum of the ages of P, Q and R is 96 years. What is the age of Q ? (i) P is 6 years older than R (ii) the total of the ages of Q and R is 56 years.

For a radioactive material, its activity A and rate of change of its activity of R are defined as A=(-dN)/(dt) and R=(-dA)/(dt) , where N(t) is the number of nuclei at time t . Two radioactive source P (mean life tau ) and Q (mean life 2 tau ) have the same activity at t=0 . Their rates of activities at t=2 tau are R_(p) and R_(Q) , respectively. If (R_(P))/(R_(Q))=(n)/(e ) , then the value of n is: