Which has more mass, a kilogram of feathers or a kilogram of iron?

Which elements do not usually interact with other elements?

A hot air balloon is filled with air through an opening the air is heated using a burner the hot air causes a pressure on the inside of the balloon use ideas about molecules to explain how the hot air causes this pressure

During which moon phase can an eclipse of the sun occur

Is a dimond a pure substance? yes or no

Batteries supply DC, direct current, which does not change in direction over time, though eventually they get exhausted.

Technician A says that engine parts should be be cleaned before a thorough test can be done to detect cracks. Technician B says that pressure testing can be used to find cracks in blocks or cylinder heads. Who is right?

How are mathematics and science related?

Radio telescopes detect waves with a wavelength of roughly 10 m. True False

2. A 0.30 kg ball is dropped onto a concrete driveway. The ball's velocity before impact is 4.5 m/s and after impact is 4.2 m/s. What is the change in the ball's momentum?

If we start with 400 atoms of a radioactive substance, how many would remain after one half-life? After 2 half-lives? After 3 half-lives? After 4 half-lives?