Which forms of matter are considered pure substances?

A elements only

B mixtures only

C compounds and mixtures

D elements and compounds

Which of these is an example of a physical change? A) sugar dissolving in warm water B) iron rusting in the presence of moist air C) wood burning in the presence of oxygen D) baking soda reacting with acid to form a gas

Examine the three listed elements of Group 13. boron (B), aluminum (Al), gallium (Ga) If boron has two energy levels, then how many energy levels do the other two elements have? Aluminum and gallium both have two energy levels.

Which stage of grieving is actually a refusal to believe the event is occurring? A. denial B. anger C. bargaining D. depression

Which of the following covalent bonds is the most polar? H-F H-C H-N H-H

What is the ph of the solution prepared by dissolving 0.927 mol hcl in enough water to make a 150 l aqueous solution?

Human muscle stores sugars in the form of

How much heat is needed to raise the temperature of 75 g of a substance by 15 C when the specific heat is 0.92 J/g-C?

A nitric acid solution flows at a constant rate of 5L/min into a large tank that initially held 200L of a 0.5% nitric acid solution. The solution inside the tank is kept well stirred and flows out of the tank at a rate of 10L/min.

How many molecules are in 237g (about a cup of water)

3. A compound was analyzed and found to contain 9.8 g of nitrogen, 0.70 g of hydrogen, and 33.6 g of oxygen. What is the empirical formula of the compound?