Which is an example of a chemical change?

a. water evaporating from a puddle

b. cloth tearing when pulled

c. wood forming sawdust when cut

d. bread baking in an oven

What are the most common student injuries in the chemistry lab and how can they be prevented

One of the most common elements is Oxygen. What are some of the characteristics of Oxygen: the atomic number, the atomic mass, the number of protons, the number of neutrons, how many valence electrons and how many energy shells?

Mixtures can be separated into their components by taking advantage of differences in the chemical properties of the components.

Identify the characteristics of earth that makes it a special place

How many moles of lithium are in 25 grams of lithium

Student follow up The ionic equation for the reaction between zinc and sulfuric acid is. Zn (s) + 2H (aq) - - Zn" (aq) + H2 (g) a State what has been oxidised in this reaction. Explain your answer in terms of electrons.

What kind of group 1 atoms are the most reactive? a. Small atoms c. Atoms with the most electrons in the valence level b. Large atoms d. Atoms at the top of the periodic table

What does it mean when there are 2.3 x 10-4 moles?

Electric force is an A. attraction and repulsion between protons and electrons . B. attraction and repulsion between protons and neutrons. C. attraction and repulsion between neutrons and electrons.

A salt crystal has a mass of 0.18 mg. how many nacl formula units does it contain?