Question

Curie is the unit of
$
  (a){\text{ decay constant}} \\
  {\text{(b) radio - activity}} \\
  {\text{(c) half life}} \\
  {\text{(d) average life}} \\
$

Answer 1

Hint – In this question think of the fact that the unit of half-life and average life is generally measured in years so this left us with two main options to choose from that is decay constant and radio-activity. In order to get the right one amongst them use the fact that radio-activity phenomena of elements is founded by Pierre Curie. This will help getting the answer.

Complete step-by-step solution -
As we know curie is not a S.I unit.
So it is given on the name of some person.
So it is named after Pierre Curie who is the inventor of radio-activity.
According to him in a paramagnetic material (i.e. material when placed in a magnetic field gets weakly magnetized in the direction of applied magnetic field) the magnetization of the material is directly proportional to the applied magnetic field and inversely proportional to the temperature.
$ \Rightarrow M \propto \dfrac{B}{T}$, where M = magnetization (A/m), B = magnetic field ($\dfrac{{wb}}{{{m^2}}}$) and T = temperature (K)
Here we apply proportionality constant C which is the first letter of the Surname of the Scientist Pierre Curie.
 $ \Rightarrow M = C\dfrac{B}{T}$, C = material specific Curie constant (K).
So Curie is the unit of radio-activity.
So this is the required answer.
Hence option (B) is the correct answer.

Note – Half-life refers to the time taken by the substance to decay half of the atoms present, and is applicable to both radioactive and non-radioactive decay. Generally the rate of decay remains constant throughout the decaying process. The average lifetime is the reciprocal of the decay constant.