MCQ
A radioactive element emits 200 particles per second. After three hours 25 particles per second are emitted. The half life period of element will be
  • A
    50 minutes
  • 60 minutes
  • C
    70 minutes
  • D
    80 minutes

Answer

Correct option: B.
60 minutes
60 minutes

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

Similar questions

A thin wire of length $l$ is carrying a constant current. The wire is bent to form a circular coil. If radius of the coil, thus formed, is equal to $R$ and number of turns in it is equal to $n$, then which of the following graphs represent $(s)$ variation of magnetic field induction $(b)$ at centre of the coil
The curvature radii of a concavo-convex glass lens are $20\, cm$ and $60\, cm$. The convex surface of the lens is silvered. With the lens horizontal, the concave surface is filled with water. The focal length of the effective mirror is $(\mu$ of glass $= 1.5$, $\mu$ of water $= 4/3)$
Which of the following statement is true
Some of the wavelengths observed in the emission spectrum of neutral hydrogen gas are $912,1026,1216,3646,6563 \,\mathring A$. If broad band light is passing through neutral hydrogen gas at room temperature, then the wavelength that will not be absorbed strongly is .................. $\mathring A$
Charges are placed on the vertices of a square as shown Let $\vec E$ be the electric field and $V$ the potential at the centre. If the charges on $A$ and $B$ are interchanged with those on $D$ and $C$ respectively, then
A magnetic needle free to rotate in a vertical plane parallel to the magnetic meridian has its north tip pointing down at $22^o$ with the horizontal. The horizontal component of the earth’s magnetic field at the place is known to be $0.35\; G$. Determine the magnitude of the earth’s magnetic field (in $G$) at the place
A metallic spherical shell has an inner radius $R_1$ and outer radius $R_2$. A charge $Q$ is placed at the centre of the spherical cavity. What will be surface charge density on the inner surface
A point source of light is used in a photoelectric effect. If the source is removed farther from the emitting metal, the stopping potential:
The magnitude of $i$ in ampere unit is
If the wavelength of light is 4000 Å, then the number of waves in 1 mm length will be