semester exam

A neutral atom of which element contains 10 electrons?

• boron

• fluorine

• lithium

• neon

Which two elements have the most similar chemical properties?

• Ci and Ar

• Be and Mg

• Na and P

• Ca and Br

Ling is learning about chemical reactions in science class. She measured out 45 grams of vinegar and 10 grams of baking soda . When she mixed them together, a bubbling reaction occurred . After the reaction stopped, she weighed the mixture and found that it weighed 54 grams.Which of the following best explains why the mixture weighed less than the original ingredients?

• Some of the vinegar evaporated during the experiment.

• The chemical reaction created a gas that left the mixture.

• The new solution is less dense than vinegar or baking soda.

• The baking soda is floating on top of the vinegar.

Which pH value indicates a basic solution?

• 1

• 5

• 7

• 12

The indicator phenolphthalein is colorless in an acid but changes color to pink in a base.A liquid with which pH would change the indicator pink?

• 3

• 5

• 7

• 9

How does the molecular motion of a substance change when it goes from liquid to solid?

• The molecules gain energy, and their relative motion increases.

• The molecules lose energy, and their relative motion increases.

• The molecules gain energy, and their relative motion decreases.

• The molecules lose energy, and their relative motion decreases.

Which type of energy is associated with the random motion of the particles in a sample of gas?

• nuclear energy

• thermal energy

• chemical energy

• electromagnetic energy

An atom of an element contains 6 protons, 6 neutrons, ans 6 electrons. An atom that is a different isotope of this element would contain

• 6 protons, 7 neutrons, and 7 electrons

• 6 protons, 6neutrons, and 7 electrons

• 7 protons, 6 neutrons,and 6 electrons

• 7 protons, 7 neutrons, and 7 electrons

Which statement best describes what happens in a fission reactions?

• Light nuclei form into heavier nuclei.

• Heavy nuclei split into lighter nuclei.

• Energy is released, and less stable element are formed.

• Energy is released, and more stable element are formed.

A science teacher heated liquid ethanol for an experiment. When he turned up the temperature, the ethanol quickly disappeared, and a strong aroma filled the room, What happened to the ethanol?

• Heating the particles in the ethanol caused them to react and bond with gases in the air, which carried the liquid ethanol particles around the room.

• Heating the particles in the ethanol removed some of their mass, decreasing their density and causing them to flow across the room.

• Heating the particles in the ethanol energized them, and they began to collide within the container until they escaped to fill the room as a gas.

• Heating the particles in the ethanol removed some of their energy, and they began to slow down and condense within the container as a solid.