What is the term for the weighted average mass of all the naturally occurring isotopes of an element? atomic mass atomic notation mass number atomic number none of the above

Which of the following is NOT a sign of a chemical reaction? absorbing light when chemicals are contacted with each other emission of light when chemicals are contacted with each other All of the above are signs of a chemical reaction. absorbing heat when chemicals are contacted with each other emission of heat when chemicals are contacted with each other

Under certain conditions the rate of this reaction is zero order in ammonia with a rate constant of $0.0026M\cdot s^{-1}$ $2NH_{3}(g)\rightarrow N_{2}(g)+3H_{2}(g)$ Suppose a 300. mL flask is charged under these conditions with 450.mmol of ammonia. How much is left 100 s later? You may assume no other reaction is important. Be sure your answer has a unit symbol,if necessary, and round it to the correct number of significant digits. $\square $

Cleaning chemicals are generally not health hazards True False

Identify the molecule or molecules containing polar covalent bonds. HF CsF $Br_{2}$ KH $N_{2}$

A saturated solution holds the maximum amount of solute under the solution conditions. True False

To identify a chemical's hazards, check its: Smell Color MSDS

A 0.788 mole sample of ideal gas at $12^{\circ }C$ occupies a volume of 4.25 L. What is the pressure of the gas? $\square $

1 124 . Select the best entires __ are the most reactive metals especially with water. Salts Halogens Alkali Noble gases Cations

Part 1: Changing the amount of Solute Solvent STEP 1: Add solute to the water by "shaking" the drink mix Make sure the concentration meter is in the water so you can read the number and unit. $\square $ $\square $

Part 4: Chemistry Experiment 2 - Vinegar and Baking Soda Reaction Scenario: You want to see if changing the amount of vinegar affects the size of the gas bubble produced when mixed with baking soda. Questions: What is the independent variable? __ What is the dependent variable? __ What are two controlled variables? __ What would be a good hypothesis for this experiment? Which group is the experimental group? __ Is there a control group? If yes, which one?If not, suggest one.