Why no machine is 100 efficiency?

How many moles are in 36 g of Beryllium (Be) ? a. 0.25 mol b. 4.0 mol c. 45.0 mol d. 320 mol

Which energy sublevel is being filled by the elements y to cd? 4d 5p 5s 5f 5d?

There are 50 billion gold atoms in every drop of sea water. 1 drop =.05ml. is it feasible to "mine" the ocean for gold? in other words, how many gallons of sea water would have to be stripped of its gold to produce 1 troy ounce of the precious metal?

Which one of the following is a solution? salt water sugar oxygen chocolate chip cookies

Brittney was babysitting for her neighbor's two-year-old and had just put little Justin down for a nap.

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?