Which explanation is based on scientific evidence? A. Observations made using microscopes reveal that all known
organisms are composed of tiny structures called cells.
B. Magnets have hidden powers that can have health effects.
C. Performing good deeds for other people will make a person happy.
D. illnesses are caused by bad smells in the air.

Suppose a comet has an orbital period of 309.1 years around the sun. what is it’s average distance from the sun?

Assume you measured the mass of the cart to be (500 ± 1) g and the mass of the additional mass you put on the cart to be (500 ± 1) g as well. since the scale you are using in the lab cannot measure objects heavier than 600g you will have to sum up individual pieces and propagate the error. so what would be the mass and the standard error of the cart and the mass

An atom that has gained or lost electrons is called an _