Question
What is radioactivity? Name two radioactive substances.
✓
Answer
Radioactivity is a nuclear phenomenon. It is the process of spontaneous emission of α or β and γ radiations from the nuclei of atoms during their decay.
Example: uranium, radium.
Example: uranium, radium.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
Define Velocity Ratio
(a) A straight wire conductor passes vertically through a piece of cardboard sprinkled with iron filings. Copy the diagram and show the setting of iron filings when a current is passed through the wire in the upward direction and the cardboard is tapped gently. Draw arrows to represent the direction of the magnetic field lines.
(b) Name the law which helped you to find the direction of the magnetic field lines.
(b) Name the law which helped you to find the direction of the magnetic field lines.
Give scientific reason for the following:
There are chances of toppling when a truck takes a sharp turn especially when it is not fully loaded
There are chances of toppling when a truck takes a sharp turn especially when it is not fully loaded
(a) Name the characteristic of sound which enables one to distinguish the sound of two musical instruments even if they are of same pitch and same loudness.
(b) Two waves of same pitch have their amplitudes in the ratio $2: 3$.
(i) What will be the ratio of their loudness?
(ii) What will be the ratio of their frequencies?
→(b) Two waves of same pitch have their amplitudes in the ratio $2: 3$.
(i) What will be the ratio of their loudness?
(ii) What will be the ratio of their frequencies?
A certain nucleus has a mass number 20 and atomic number 9. Find the number of neutrons and protons present in it.
What do you understand by the clockwise and anticlockwise moment of force? When is it taken positive?
State two applications of echo.
State two uses of ultraviolet radiation.
A substance undergoes (i) a change in its temperature, (ii) a change in its phase without change in its temperature. In each case, state the change in energy of molecules of the substance.
(a) draw a V-I graph for a conductor obeying Ohm’s law.
(b) what does the slope of V–I graph for a conductor represent?