The correct option is (c) 2 and 3 only.
Explanation
Intrusive igneous rocks, also known as plutonic rocks, are formed when magma cools and solidifies deep within the Earth's crust.
- Statement 1 is Incorrect: Rocks formed when molten lava cools on the surface are classified as extrusive igneous rocks (or volcanic rocks). Intrusive rocks form deep beneath the surface, not on it.
- Statement 2 is Correct: Since these rocks form deep underground, the surrounding country rocks insulate the magma, causing it to cool very slowly. This slow cooling process allows sufficient time for mineral crystals to grow large, resulting in a coarse-grained texture.
- Statement 3 is Correct: Granite is a classic example of an intrusive igneous rock. It typically consists of large, visible crystals of quartz, feldspar, and mica.
Key Takeaway: Intrusive (Plutonic) rocks form deep underground, cool slowly, and possess large grains (e.g., Granite). Extrusive (Volcanic) rocks form on the surface, cool rapidly, and possess fine grains (e.g., Basalt).