Fill in the blanks.

1. Processes such as ___________, ____________ and ____________ modify the earth's surface.
2. Most _____________ starts on exposed surface of rocks and minerals.
3. ______________ and ____________ cause rocks to weaken and crumble.
4. Soil creep is an _____________ of weathering.
5. ______________ is necessary for growth of any kind of vegetation.
6. ______________ rocks undergo changes with temperature and pressure.

Match the following:

Write 'T' for True and 'F' for False.

1. Over grazing by animals conserves soil.
2. Weathering is a dynamic process.
3. Materials transformed into soil in their place of origin are called transported soil.
4. Due to weathering rocks get disintegrated and their loose form gets cracked.
5. Weathering is an external process.
6. Denudation occurs in weathering as well as in erosion.
7. Sedimentary rocks are formed by lave of volcanic eruptions.

Choose the correct answer.

1. Mechanical weathering produces
   1. Clay minerals
   2. Quartz
   3. Smaller particles
   4. Calcium carbonate
2. Which of the following affect the rate of weathering?
   1. The soil type and extent
   2. The rock type
   3. The climate
   4. All of these affect weathering rates
3. Soil is composed of
   1. Organic matter produced by organisms
   2. Fragments of bedrock
   3. Clay minerals formed by the chemical alteration of bedrock
   4. All of these
4. Which of the following statements about weathering is false?
   1. Rocks of different compositions weather at different rates
   2. Heat and heavy rainfall increase rate of chemical weathering
   3. The presence of soil slows down the weathering of the underlying bedrock
   4. The longer a rock is exposed at the surface, the more weathered it becomes
5. Hydration occurs when
   1. Rock becomes hard
   2. Chemical reaction between hydrogen in the rainwater and minerals in the rock
   3. Excessive heat
   4. All of the above

What is gradation? Name the agents of gradation.