A radioactive nucleus can decay by two different processes. Half-… - Vidyadip

MCQ

A radioactive nucleus can decay by two different processes. Half-life for the first process is $3.0\, hours$ while it is $4.5\, hours$ for the second process. The effective half- life of the nucleus will be $.........\,hours.$

A
$3.75$
B
$0.56$
C
$0.26$
✓
$1.80$

✓

Answer

Correct option: D.

$1.80$

d
$\lambda_{\text {eq }}=\lambda_{1}+\lambda_{2}$

$\frac{\ln 2}{\left( t _{1 / 2}\right)_{ eq }}=\frac{\ln 2}{\left( t _{1 / 2}\right)_{1}}+\frac{\ln 2}{\left( t _{1 / 2}\right)_{2}}$

$\left( t _{1 / 2}\right)_{ eq }=\frac{\left( t _{1 / 2}\right)_{1} \times\left( t _{1 / 2}\right)_{2}}{\left( t _{1 / 2}\right)_{1}+\left( t _{1 / 2}\right)_{2}}$

$=\frac{3 \times 4.5}{3+4.5}=\frac{3 \times 4.5}{7.5}=\frac{3 \times 3}{5}=1.8 \; hr$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "M.C.Q (1 Marks)" from 13. Nuclei→13. Nuclei — all question types→Physics STD 12 Science question papers→CBSE Board STD 12 Science question papers→CBSE Board question paper generator→

Similar questions

A long solenoid has $200$ $turns$ per $cm$ and carries a current $i$. The magnetic field at its centre is $6.28 \times 10^{-2} $ $\frac{{Wb}}{{{m^2}}}$ Another long solenoid has $100$ $turns$ per $cm$ and it carries a current $\frac{I}{3}\;$ . The value of the magnetic field at its centre is

Retina of eye acts like ........ of camera

The equivalent resistance between points $A$ and $B$ in the given network is ............ $\Omega$

Find magnetic field at centre $P$ if length of side of square loop is $20\, cm$

The de Broglie wavelength associated with a ball of mass $150g$ travelling at $30\ ms^{-1}$ is:

In two separate experiments the neutral points due to two small magnets are at a distance of r and 2r in broad side-on position. The ratio of their magnetic moments will be

Two mutually perpendicular conductors carrying currents $I_1$ and $I_2$ lie in one plane. Locus of the point at which the magnetic induction is zero, is a

A scientist claims to have a perfect technique in which he can spontaneously convert an electron completely into energy in the laboratory without any other material required. What is the conclusion about this claim from our current understanding of physics?

Assertion : The ion cannot move with a speed beyond a certain limit in a cyclotron.
Reason : As velocity increases time taken by ion increases.

Ray optics fails when