Answer:
1. 6 significant digits. 2. 2 significant digits. 3. 8 significant digits. 4. 4 significant digits. 5. 8 significant digits. 6. 7 significant digits. 7. 2 significant digits.
Explanation:
All nonzero digits are significant. All zeros before nonzeros are insignificant. All zeros after nonzeros are insignificant unless they are made for precision of some data. So 405000 may have 3 or 6 significant figures. But usually all zero figures after significant digits are significant.
Scientists believe that the solar system was formed when a cloud of gas and dust in space was disturbed, maybe by the explosion of a nearby star(called a supernova). This explosion made waves in space which squeezed the cloud of gas and dust.
