A) Dormant volcano:
A dormant volcano, also known as a sleeping volcano, is a volcano that is currently not erupting but has the potential to erupt in the future. It is in a state of temporary inactivity and can become active again.

Key points about dormant volcanoes:
- Temporary inactivity: Dormant volcanoes have not erupted for a long period of time, but they have the potential to erupt again in the future.
- Internal heat and pressure: The magma chamber beneath a dormant volcano is still filled with molten rock, which generates heat and pressure. This indicates that the volcano is still alive and can potentially erupt.
- Signs of activity: Although dormant volcanoes are not currently erupting, they may still show signs of activity such as gas emissions, ground deformation, or increased seismic activity. These signs indicate that the volcano is slowly reawakening.

b) Active volcano:
An active volcano is a volcano that has recently erupted or is currently erupting. It is in a state of constant activity, with regular eruptions and volcanic phenomena occurring.

Key points about active volcanoes:
- Ongoing eruptions: Active volcanoes are characterized by frequent eruptions. The frequency and intensity of eruptions can vary, ranging from small lava flows to explosive eruptions that eject ash, gases, and volcanic bombs.
- Volcanic phenomena: Active volcanoes exhibit various volcanic phenomena such as lava flows, pyroclastic flows, ash clouds, and volcanic gases. These phenomena are a result of the release of magma from the Earth's crust.
- Potential hazards: Due to their constant activity, active volcanoes pose significant hazards to nearby communities and the environment. These hazards include lava flows, ashfall, pyroclastic flows, lahars (mudflows), and volcanic gases. Proper monitoring and preparedness are essential to mitigate the risks associated with active volcanoes.

c) Extinct volcano:
An extinct volcano is a volcano that is unlikely to erupt again in the future. It is considered dead and has no remaining magma or potential for future volcanic activity.

Key points about extinct volcanoes:
- Lack of recent activity: Extinct volcanoes have not erupted for thousands or even millions of years. They show no signs of recent volcanic activity.
- Erosion and weathering: Over time, extinct volcanoes undergo significant erosion and weathering. Their volcanic cones may be eroded, and their craters may be filled with sediment or transformed into lakes.
- Geological changes: The lack of volcanic activity in extinct volcanoes is often attributed to changes in the geological processes and movements of tectonic plates. These changes can cause the magma source to become depleted or cut off, rendering the volcano extinct.
- Geological records: Scientists determine whether a volcano is extinct based on geological and historical records. They analyze the volcano's past eruptions, age, and geological features to assess the likelihood of future activity. If a volcano has been inactive for an extremely long time and shows no signs of activity, it is classified as extinct.

Dormant volcano - a volcano that has not erupted for a long time, but had a chance to erupt again