List of top Physics Questions on Decay Rate asked in MET

Half-life period of a radioactive substance is \(10\,\text{min}\). Then amount of substance decayed in \(40\,\text{min}\) will be:
Fraction decayed in 6 days is \(7/8\). Find fraction decayed in 10 days.
A wet open umbrella is held vertical and it whirls about the handle at a uniform rate of 21 revolutions in \(44\ \text{s}\). If the rim of the umbrella is a circle of \(1\ \text{m}\) in diameter and the height of the rim above the floor is \(4.9\ \text{m}\), the locus of the drop is a circle of radius
The moment of inertia of a body about a given axis is \(1.2\ \text{kg·m}^2\). To produce a rotational kinetic energy of \(1500\ \text{J}\) an angular acceleration of \(25\ \text{rad/s}^2\) must be applied for
Rn decays into Po by emitting an \( \alpha \)-particle with half-life of 4 days. A sample contains \( 6.4 \times 10^{10} \) atoms of Rn after 12 days, the number of atoms of Rn left in the sample will be:
Decay constant of radium is \( \lambda \). By a suitable process its compound radium bromide is obtained. The decay constant of radium bromide will be:
A freshly prepared radioactive source of half-life 2 h emits radiation of intensity which is 64 times the permissible safe level. Calculate the minimum time after which it would be possible to work safely with this source.
The reaction involved in the oil of winter green test is salicylic acid + missing reagent $\xrightarrow{\Delta, \text{Conc. H}_{2}\text{SO}_{4}}$ product. The missing reagent in the above reaction is
A covalent molecule $AB_{3}$ has pyramidal structure. The number of lone pair and bond pair of electrons in the molecule are respectively
A radioactive substance has a half-life of 60 min. During 3 hours, the fraction of the substance that has decayed is:
The half-life of a radioactive element is 10 days. The time required for 75% of the element to decay is: