Final answer:
The force applied on a balance when the pointer points to 100g is approximately 1 N, after converting the mass to weight using the formula W = mg and factoring in Earth's gravity.
Step-by-step explanation:
When applying a force on the pan of a single pan weighing balance, and the pointer points to 100g, the force you are applying is not measured in grams, which is a unit of mass, but in newtons (N), which is the unit of force. To convert mass to weight (which is a force due to gravity), you use the equation W = mg, where m is the mass and g is the acceleration due to gravity (approximately 9.8 m/s² on Earth).
Therefore, a mass of 100g is equivalent to 0.1 kg (since 1000g = 1kg), and the force in newtons can be calculated by multiplying this mass by the acceleration due to gravity:
W = (0.1 kg)(9.8 m/s²) = 0.98 N.
Thus, the closest answer to the force you applied would be 1 N when rounded to one significant figure, which makes option B) 1 N the correct answer.