Which sample is a pure substance?

A. a test tube of zinc oxide

B. a container of zinc and oxygen

C. a flask of pond water

D. a jar of soil

UILS Why is soap used to remove grease?

3.) What type of energy is released with the faucet? * A.) light B.) electrical C.) mechanical 4.) What type of energy from the sun? * A.) light B.) electrical C.) mechancial

Indicate whether each source is reliable or unreliable a goverment website a university professor's personal blog a commercial website an online peer-reviewed science journal

How was the first periodic table of the elements organized?

Consider these changes. (a) Hg (l) - >Hg (g) (b) 3O2 (g) - >2O3 (g) (c) CuSo4*5H2O (s) - >CuSO4 (s) + 5H2O (g) (d) H2 (g) + F2 (g) - >2HF (g) At constant pressure, in which of the reactions is work done by the system on the surroundings?

Convert: 65 kg to mg 65,000 mg O 65,000,000 mg O 65 mg

F. How many representative particles are in 6.78 moles of sucrose C12H22011?

The ratio of the lengths of two sides of a right triangle forms a

What element is used in making thermometers

How many dots are shown in the electron dot diagram for calcium, in group II and period 4 with 20 protons and 20 electrons? a. four c. eight b. two d. twenty