Quiz on Igneous Rocks

What causes igneous rocks to form?

• Cooling of molten magma underground

• Layers of fossils pressed together

• Compression of plant materials

• Breakdown of older rock fragments

Why are igneous rocks called primary rocks?

• They are formed before other rocks

• They are made from soft materials

• They are found on mountain tops

• They are formed by flowing water

Which rock forms when lava cools quickly?

• Basalt with small dark crystals

• Granite with large light crystals

• Limestone with trapped fossils

• Dolerite with medium hard crystals

What type of rock is granite?

• Intrusive rock formed deep inside

• Extrusive rock formed on surface

• Sedimentary rock formed in lakes

• Metamorphic rock formed by heat

What helps crystals grow larger in rocks?

• Slow cooling of magma below crust

• Fast movement of rivers and winds

• Repeated layering of sediments

• Softening due to water and air

What is a feature of extrusive rocks?

• Small crystals and dark texture

• Large crystals and shiny color

• Fossils trapped between layers

• Soft texture and smooth layers

What best describes dolerite?

• Formed at an intermediate depth

• Formed on ocean floor surface

• Formed by cooling of limestone

• Formed with fossil remains

Which rock is common in Deccan Plateau?

• Basalt with fine dark crystals

• Granite with shiny white grains

• Shale with soft layered structure

• Limestone with shell deposits

Why are igneous rocks useful in roads?

• They are hard, compact and strong

• They are soft, brittle and shiny

• They are layered and porous too

• They are rich in fossil remains

Which is a use of igneous rocks?

• Building, grinding and minerals

• Fertiliser, fuel and clay work

• Salt, coal and iron smelting

• Oil drilling and making chalk