Which one of these equations is balanced? a. Zn + 2hcl - - > ZnCl2 + H2 b. S8 + 24F2 - - > 8SF6

a

b

a and b

neither

In a magazine, you read that two scientific investigations attempted to answer the same question. However, the two teams of scientists came to opposite conclusions. How do you decide which investigation was valid?

Write the complete balanced equation for the reaction between AlF3 and CaO.

Who was the first chemist to organize elements by atomic number?

Which of the following elements is the most reactive? potassium, lithium sodium, or rubidium

Rocks formed from particles deposited by wind and water

Hydrochloric acid is purchased in 12 molar concentrations. If I needed 200 ml of 2.0 molar HCl, how many milliliters of the concentrated solution would I need

Which of the following represents a chemical change? Bending a wire Freezing of water Fireworks exploding Melting of a wax candle

5.00 L of a gas is collected at 100K and then allowed to expand to 20.0 L. What must the new temperature be in order to maintain the same pressure? A. 400 °C B. 127 °C C. 223 °C D. 627°C

Before the initial explosion was the matter hot or cold

Which of the following atoms has seven valence electrons? chlorine (Cl) nitrogen (N) manganese (Mn) oxygen (O)