• Statement-I: Rainfall is one of the reasons for weathering of rocks. This is true because rainwater, which is slightly acidic due to the presence of dissolved gases like carbon dioxide, can react with minerals in rocks and cause them to break down over time.
• Statement-II: Rain water contains carbon dioxide in solution. Rainwater contains dissolved gases like oxides of carbon, nitrogen, and sulfur, resulting in a slightly acidic pH. Normal rainwater has a pH of around 5.6, making it slightly acidic due to the dissolution of carbon dioxide (CO2), which creates weak carbonic acid.
• Statement-III: Rain water contains atmospheric oxygen. As raindrops fall, their oxygen concentration increases because they become saturated with atmospheric oxygen.
• Therefore, both Statement-II and Statement-III are correct and they both explain how rainfall can contribute to the weathering of rocks (Statement-I).

• Pyroclastic debris: Pyroclastic flows are a product of volcanic eruptions and are composed of hot ash, rock fragments, and gases.
• Ash and dust: Ash and dust are also products of volcanic eruptions, formed from the eruption of volcanic particles and gases.
• Nitrogen compounds: Nitrogen compounds, such as nitrogen gas, can be released during volcanic eruptions as part of the gases emitted.
• Sulphur compounds: Sulphur compounds, such as sulfur dioxide and hydrogen sulfide, are common volcanic gases that are released during eruptions.

•   In a seismograph, P waves are recorded earlier than S waves. P waves are primary waves that travel faster through the Earth's interior compared to S waves.

•   In P waves, the individual particles vibrate to and fro in the direction of wave propagation, which is longitudinal motion. In contrast, S waves have transverse motion, where the particles vibrate up and down at right angles to the direction of wave propagation.

•   Damodar is an east flowing river with rift valley due to down warping. Down warp denotes a segment of the earth's crust that is broadly bent downward.

•   Damodar River is a river flowing across the Indian states of Jharkhand and West Bengal. Rich in mineral resources, the valley is home to large-scale mining and industrial activity.

•   Major Geological Eras 

•   Peninsular and Periods

A. Deccan Traps  - Cretaceous era

B.Western Ghats  - Late cenozoic era

C.Aravalli  - Pre-cambrian era

D.Narmada-Tapti - Pleistocene period alluvial deposits

•   The palaeomagnetic results indicate that, the Indian land mass has moved to the north breaking from Africa.

•   Geologists believes that the Indian peninsula was a part of the Gondwanaland (continent) which drifted northwards, and India, Africa and other parts separated from each other.

•   The running water cuts through the clayey soils and makes deep channels known as Gullies. This type of erosion is called gully erosion. Gully erosion can be found in the Chambal basin where it is called Ravines.

•   Barkhan is a crescent-shaped sand dune produced by the action of wind predominately from one direction. One of the commonest types of dunes, it occurs in sandy deserts all over the world.

•   Note- More about Classification of Rocks is explained in Q. no. 50.

Different types of peninsular include capes, headlands, promontories, points, spits, and bill.

1. A point in geography is a type of peninsula that is often very narrow and tapers towards the end.
2. A spit in geography is a type of peninsula that is often sandy, descents down as it protrudes away from the mainland, and is usually formed by wave action.
3. A promontory is a raised landmass that protrudes from a lowland or a waterbody. When it protrudes in a water body, it is a peninsula. Headlands are types of promontories that descend steeply into water bodies. A very large headland is referred to as a Cape. A very narrow promontory is called a Bill in geography.

Conditions favorable for the formation of the Deltas:

1. Active vertical and lateral erosion in the upper course of the river to provide extensive sediments to be eventually deposited as deltas.

2. The coast should be preferably tideless.

3. The sea adjoining the delta should be shallow or else the load will disappear in the deep waters.

4. There should be no large lakes in the river course to filter-off the sediments and there should be no strong current running at right angle to the river mouth, washing away the sediments.

Asia and Africa had a single landmass since there are many evidences to this fact.

•   Findings of same type of fossils in both the continents.

•   Desert regions in both the regions

•   There is also similar climate in certain regions of both the continents

•   Earthquakes are caused due to the tectonic motions of the earth.

•   The main cause of an Earthquake is the release of energy from the Earth’s crust in the form of Seismic Waves that travel in all directions. These vibrations that arise from Earthquakes are measured on instruments known as seismographs.

•   Earthquake is defined as sudden shaking of the earth’s surface.

•   Fossils are most commonly found in sedimentary rock among the three major rocks. Unlike most igneous and metamorphic rocks, sedimentary rocks form at temperatures and pressures that do not destroy fossil remains. Palaeontologists use fossils as a record of the history of life. Fossils are also extremely useful for understanding the ancient environment that existed in an area when they were alive.