The rate of decay of a radioactive substance at any time is proportional to its mass at that instant. If `m_(0)` be the mass of the substance at time t=0, find the law of variation of its mass as a function of time t.

In a certain culture the rate of increment of bactreria at any instant is proportional to the cube root of the number of bacteria present at that instant. If the number of becteria becomes 8 times hours, in how much time that number becomes 64 times?

In a certain culture the rate of increment of bacterial at any instant is proportional to the cube root of the number of bacteria present at that instant. IF the number of bacteria becomes 8 times in 3 hours, in how much time that number becomes 64 times?

A radioactive substance is subject to the law of natural decay (dv)/(dt)=-kv where v is the valume of the substance at time t and k is a positive constant. If 40% of the substance disappear in 25 years, find the time it takes to disappear 60% of the substance.

Half-life of a radioactive substance is 20 minute. The time between 20% and 80% decay will be

A radioactive substance is subject to the law of natural decay (dv)/(dt)=-kv , where v is the volume of the substance at time t and k is a positive constant. The half-life of the substance is the time it takes for half the substance to disappear. Calcualte the half-life if 20 % of the substance disappeared in 15 years.

A particle of mass m is driven by a machine that delivers a constant power k watts. If the particle starts from rest the force on the particle at time t is

The number of atoms of a radioactive substance of half-life T is N_(0) at t= 0. The time necessary to decay from N_(0)//2 atoms to N_(0)//10 atoms will be

Mass m of a substance requires an amount H of heat for a rise t in temperature. If the specific heat of the substance be s, then its water equivalent is

The half-life of a radioactive substance is 20 min. The approximate time interval (t_2-t_1) between the time t_2 when 2/3 rd of its has decayed and time t_1 when 1/3 rd of it had decayed is - (A) 14 min (B) 20 min (C) 28 min (D) 7 min

At STP, the volume of 1 g of a gaseous substance is 280 mL. find its relative molar mass.