Question

1. which of the following must be worn during the lab?

a. goggles
b. apron
c. closed - toe shoes
d. all of the above

1. which of the following energy types is not found in a moving car?

a. potential energy
b. kinetic energy
c. chemical energy
d. thermal energy

1. if i need to measure out 87ml of water, i should probably use a but if i need to measure out exactly 100ml of water, i should probably use a
2. heat flows from to
3. label below which is endothermic and which is exothermic.

campfire burning ice melting water freezing in a freezer eggs in a frying pan.

1. the cathode ray tube experiment showed a cathode ray bending towards a magnet, proving that atoms contain a negatively charged
2. the nucleus of the atom contains and the latter of which have a charge
3. you discover an element with the following masses and abundances: 50amu (4.35%), 52amu (83.79%), 53amu (9.50%) and 54amu (2.36%). what is the average atomic mass?

Explanation:

Step1: Answer question 1

In a lab, goggles protect eyes, apron protects clothes and closed - toe shoes protect feet. So all are required.

Step2: Answer question 2

A moving car has kinetic energy (due to motion), potential energy (e.g., gravitational potential depending on height), and thermal energy (from friction etc.). Chemical energy is stored in fuel and not an energy type directly associated with the moving car's motion.

Step3: Answer question 3

For 87 ml of water, a graduated cylinder can be used as it can measure non - exact volumes with good precision. For exactly 100 ml, a volumetric flask is more appropriate as it is designed for measuring exact volumes.

Step4: Answer question 4

Heat flows from a higher temperature region to a lower temperature region according to the second law of thermodynamics.

Step5: Answer question 5

A campfire burning is exothermic (releases heat). Ice melting is endothermic (absorbs heat). Water freezing in a freezer is exothermic (releases heat to the freezer). Eggs in a frying pan is endothermic (absorbs heat from the pan).

Step6: Answer question 6

The Cathode Ray Tube Experiment showed that atoms contain a negatively charged particle called an electron.

Step7: Answer question 7

The nucleus of an atom contains protons and neutrons. Protons have a positive charge.

Step8: Answer question 8

The formula for average atomic mass is $\sum_{i} (m_i\times \%a_i)$, where $m_i$ is the mass of the isotope and $\%a_i$ is its abundance.
\[

$$\begin{align*} &(50\times0.0435)+(52\times0.8379)+(53\times0.0950)+(54\times0.0236)\\ =&2.175 + 43.5708+5.035+1.2744\\ =&52.0552\text{ amu} \end{align*}$$

\]

Answer:

1. d. All of the above
2. c. Chemical energy
3. Graduated cylinder; Volumetric flask
4. Higher temperature region; Lower temperature region
5. Campfire burning: Exothermic; Ice melting: Endothermic; Water freezing in a freezer: Exothermic; Eggs in a frying pan: Endothermic
6. Electron
7. Protons; Neutrons; Positive
8. 52.0552 amu