Statement-I is incorrect because giant stars, despite their larger size and luminosity, actually have shorter lifespans than dwarf stars, primarily due to their higher mass leading to faster consumption of nuclear fuel. Statement-II is correct as giant stars undergo a much greater rate of nuclear reactions, which fuels their brightness but also contributes to their rapid evolution and shorter life cycle compared to the more stable dwarf stars. This comparison reflects the fundamental relationship between mass, energy consumption, and stellar evolution, which is a key concept in astrophysics as covered in standard UPSC study materials.