How many electrons are in the nucleus of an atom with an atomic number of 20?

There are many different types of objects in the solar system. Which type of object is the Sun?

If a ruler is marked off by 1 centimeter increments, give an example of a measurement that could be made using that ruler. Be careful to give the measurement using the correct significant figures.

How many Chlorine atoms are in 2.5 moles of CaCl2?

The basic unit of a chemical unit

Write the concentration equilibrium constant expression for this reaction. Cu (s) + 2Ag + (ag) - > Cu2 + (aq) + 2Ag (s)

Which physical method can be used for obtaining a sample of salt from a small beaker of salt water? boiling freezing chromatography sorting

Science is a unique field of thought because it relies on to describe the world. •Observations and experim •Teachers and students •Books and writings •Scientists and statements

Hemoglobin, a protein in red blood cells, carries o2 from the lungs to the body's cells. iron (as ferrous ion, fe2+) makes up 0.33 mass % of hemoglobin. if the molar mass of hemoglobin is 6.8 Ã 104 g/mol, how many fe2 + ions are in one molecule?

What could you predict about a methane molecule that would most likely be made by using both the quantum model of the atom and John Dalton's model?

What is the molar mass of an unknown hydrocarbon whose density is measured to be 1.97 g/l at stp?