Which element is present in every organic compound?

(1) carbon (3) nitrogen

(2) fluorine (4) oxygen

Why do scientists need scientific models? They can often be used to make predictions. Once established, they become fairly rigid and rarely change over time. They exactly present the scientific principle being demonstrated.

A base is added to an acid during a titration. A pH meter is used to monitor the reaction's progress. When should the addition of base stop?

Potassium carbonate dissolved in water

Why is it necessary to obtain 25 to 50 hairs from this woman?

N two or more complete sentences explain how to balance the chemical equation and classify its reaction type. ___NaI + ___Pb (SO4) 2 ⟶ ___PbI4 + ___Na2SO4

Which one doesnt belong in the list below? A. a meter B. one liter C. One centimeter D. one kilometer

Which elements did curies discover

When rubidium metal is exposed to air, two atoms of rubidium, Rb, combine with one atom of oxygen. If 1.98 grams of rubidium is exposed to air, what will be the mass of the product in grams

Fission reactions can get of of control without what taking place?

In which main energy level does the 's' sublevel first appear? K (first main energy level) L (second main energy level) M (third main energy level) N (fourth main energy level)