MCQ Detailed View

Sedimentary rocks are one of the three major types of rocks found on Earth. They form when small particles of minerals, sand, silt, clay, or organic matter are deposited over time, often in water bodies like rivers, lakes, and oceans. These materials settle layer by layer and are compressed and cemented together, creating solid rock formations.

A key feature that makes sedimentary rocks different from igneous or metamorphic rocks is that they are porous. Porosity means the rock has tiny holes or empty spaces between its grains. These spaces allow fluids like water, oil, or natural gas to pass through or stay stored inside the rock. This is why sedimentary rocks are important for groundwater reservoirs and petroleum reserves.

Examples of sedimentary rocks include sandstone, limestone, shale, and conglomerate. Many sedimentary rocks contain fossils, which are preserved remains of plants and animals from ancient times. These fossils help scientists learn about Earth's history and past life forms.

Now, looking at the other options:

• 
  

  Hard: Some sedimentary rocks can be hard, but hardness is not their main characteristic.

  
  


• 
  

  Rough: The surface texture can vary, so this is not a defining property.

  
  


• 
  

  Brittle: Certain sedimentary rocks may break easily, but not all do.

  
  


• 
  

  Volcanic: Volcanic rocks belong to the igneous rock category, not sedimentary.

  
  

Therefore, the correct answer is Porous. This porosity is what makes sedimentary rocks unique and significant in geology, hydrology, and environmental science, making this concept a vital part of Everyday Science knowledge.