What is the escape speed from a planet with mass 9×1023kg and radius 2.5×106m? (G\=6.67×10−11N m2/kg2)
ve = 2GMR. ve = 2×6.67×10−11×9×10232.5×106. ve = 4.801×107≈6.93×103m/s≈6.9km/s. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 6.9 km/s. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.
Ref: Halliday & Resnick, Fundamentals of Physics, 11th ed., Chapter 13: Gravitation.