By observing sunspots, galileo concluded that the sun

concluded that the sun was rotating.

Explanation:

It concludes that the sun is rotating.

When observing and studying sunspots, Galileo concluded that due to the movement of the spots the sun must be rotating.

This discovery that the sun is rotating led to Galileo to the idea that the earth was probably also rotating and therefore the model that the earth was still and that everything else revolved around was challenged by Galileo's ideas, which were controversial at the time but based on experimental evidence unlike many theories accepted in those times.

Thus, the solar spots studied by Galileo showed that the sun was rotating.

answer: 2×10^-2kg

explanation: density= mass per volume

vol=mass/density

converting to s.i units we have;

3÷1000kg = 0.003

1.5÷100m = 0.15

0.003/0.15 = 0.02kg