What are the only elements that exist in nature as uncombined atoms?

If the pH of a solution is 6.2 what is the [H+]?

Interpret and describe an example of a chemical formula. Summarize the two parts a chemical formula must have.

What is igneous rock made of

As an aqueous solution becomes more acidic the hydroxide ion

Which of the following is a possible set of quantum numbers for an electron? A.) (1,1,0+1/2) B.) (2,1,2,+1/2) C.) (4,2,0,-1/2) D.) (3,-2,1,-1/2)

Draw the organic product of the following nucleophilic reaction

How does the energy of the activated complex compare with the energies of reactants and products? select one: a. it is lower than the energy of both reactants and products. b.

A student asked to convert measurements from liters to mililiters and from mililiters to liters. His answers are shown in bold in the choices shown below. On which choice did he make a mistake?

Donald is making a model of a nitrogen atom. The box for nitrogen in the periodic table is shown. To represent a neutral atom, which of these must Donald include in his model?

What are the charges and relative masses of the 3 main subatomic particles