How long did it take the world population to increase from 1 billion to 2 billion

What is Neons group and periodic number?

An unknown substance has a mass of 15.5 g. When the substance absorbs 1.395*102 J of heat, the temperature of the substance is raised from 25.0 ∘C to 45.0 ∘C. What is the most likely identity of the substance?

Why is it important that scientific knowledge changes?

A salt crystal has a mass of 0.18 mg. how many nacl formula units does it contain?

Room temperature is often assumed to be 25∘c. Calculate the molar volume of an ideal gas at 25∘c and 1 atm pressure.

How is the mole similar to a dozen?

What element with the highest electronegativity value? Cesium calcium helium fluorine

How many neutrons and electrons are in Oxygen⁻¹⁷ isotope?

What is science all about?

What type of change is a substance that changes form but remains the same?