Question 1

Which of the following is true about fusion?

Accepted Answer

The fusion reaction occurs in the sun. We have discovered how to create manmade fusion as well, but not in a manner that can be used in homes for power (think explosions). Additionally, in the fusion process one larger molecule is created out of 2 or more smaller molecules.

Question 2

Which of the following is not a rule when calculating the significant figures in a number?

Accepted Answer

Zeroes are not always significant. For example, in the number 10,000 has 2 significant figures: the one and the last zero on the right. If the number were written as 10,000.0 then it would have 6 significant figures, due to the decimal point.

Question 3

Charlie is calculating the average test scores for his class. The students are graded from 1-100, in whole numbers. If Charlie averages all the numbers, how many significant figures should his answer have?

Accepted Answer

Because the inputs (individual test scores) each have only 2 significant figures, then the output has a maximum of 2 significant figures. Thus, the average should also be reported to the nearest whole number.

Question 4

Charles is trying to move a heavy boulder up a hill, but is having some trouble. Sam tells him that rolling it up the hill will be much easier than lifting it. This is because:

Accepted Answer

When rolling the boulder, less work is done. This is because the force exerted by gravity on the boulder will no longer have to be borne by Charles. Instead he only has to produce enough work to overcome the height of the hill.

Question 5

The term light year is often used in physics to represent:

Accepted Answer

A light year is used to represent distance, and is the distance that light travels over the course of a year (very far). 1 light year is equivalent to 9.4605284 × 10¹² kilometers.

Question 6

During the process of radioactivity, small particles are emitted from the atom or molecule in question. Which of the following types of particles can be emitted during radiation? I. Electrons
II) Neutrons
III) Photon

Accepted Answer

In radiation, electrons, photons, alpha particles, and in some rare cases, positrons can be emitted. Neutrons are emitted from the normal kinds of radiation (alpha, beta, and gamma). Photons results from gamma radiation, and contain very high amounts of energy, which is why gamma radiation is the most dangerous.

Question 7

A new gas has been found that has a volume of 22.4 liters at room temperature and atmospheric pressure. Which of the following is needed to determine the molecular weight of this gas?

Accepted Answer

Given the volume at STP (standard temperature and pressure), we know that we have 1 mole of the gas. This can be found using the ideal gas law. 1 mole of gas at room temperature and 1 atmosphere occupies just about 22.4 liters. Thus, if we know the density as well, then the molecular weight can easily be determined.

Question 8

Which of the following metals is not an element?

Accepted Answer

Steel is not an element, and is a mixture of carbon, manganese, silica, iron, nickel, and chromium, among others. It is an alloy, and not a pure individual element. The other answer choices are all found on the periodic table.

Question 9

Which of the following type of bond is the strongest?

Accepted Answer

A covalent bond is one of the strongest types of bonds, and has similar strength to an ionic bond (not in the list). Van der Waals, London dispersion, and Hydrogen bonds are all relatively weak. Sulfide bonds occur as an interaction between sulfide functional groups and possess decent strength, but not nearly as much as a covalent bond.

Question 10

Statistics are often used to determine whether or not an experiment provides enough accuracy to believe the results beyond a reasonable doubt. What confidence level is typically needed for a science experimental result to be considered valid?

Accepted Answer

Typically, a p-value of 0.05, meaning only a 5% chance the result was obtained by chance, is needed. This is a 95% confidence. The confidence level requirement can vary depending on your field, but in general if you receive a 95% confidence level from your statistical analysis, most scientists will agree that your results are significant.

Question 11

Which of the following actions does not involve work being done on an object?

Accepted Answer

Work is defined as a force applied across a distance, meaning the force needs to be in contact with the object. In the case of a soccer ball flying through the air, there is no force applied to the ball, other than gravitational force, which is not considered work being done. The other examples all have a force (person, forklift) doing work on an object.

Question 12

An elastic collision is best defined as what?

Accepted Answer

Kinetic energy is conserved before and after an elastic collision. In nature, there is no such thing as a perfectly elastic collision due to friction or air resistance forces, meaning some kinetic energy is always lost when objects collide.

Question 13

John is learning chemistry for the first time, and he is told by his teacher that water is not in a "perma-cool" state, but rather a solid state. Which of the following is also not a state of matter?

Accepted Answer

Fixed matter is not a type of matter. Plasma is superheated matter which isn't quite a gas, and is electrically conductive and responds to magnetic or electromagnetic forces. The common types of matter are solid, liquid, or gas.

Question 14

John is now trying out his first chemistry experiment. He is given a sample of phosphorus, which is a solid at room temperature. John slowly heats the phosphorus from room temperature to 200°C. Which of the following will likely occur during this experiment?

Accepted Answer

The phosphorus will likely turn into a liquid when heated to 200°C. Phosphorus has a melting point of around 50-60°C, depending on the purity of the compound. The phosphorus should not turn into a gas or catch on fire until a much higher temperature!

Question 15

Water, and many other molecules, exhibit a type of bond called hydrogen bonding. Hydrogen bonding is caused by:

Accepted Answer

A hydrogen bond is formed through an attractive interaction between two polar molecules. Water is an example of a very polar molecule, due to the electronegativity difference between oxygen and the two hydrogens in the molecule.

Question 16

Which of the following is not a metric unit of measurement?

Accepted Answer

A gallon is not a metric unit of measurement, and is an English unit of volume. The metric units for volume include milliliter and liter. The mole is a unit used in both metric and English units, and represents the Avogadro's number (6.022 x 1022) of atoms or molecules.

Question 17

Which of the following is an allotrope of carbon?

Accepted Answer

Graphite is an allotrope of carbon, as well as diamond or graphene. Allotropes are different forms of a pure element. For example, oxygen can be found as O? or O? in nature, as well as occasionally in its monomeric form, O^-2

Question 18

Alexi is performing a chemical reaction in a solution of water, seen below: MgCl₂(aq) + PbSO?(aq) <-> MgSO?(aq) + PbCl₂(s) Alexi finds that PbCl₂, lead chloride, is not soluble in water, and that the equation above is written incorrectly. Why is the equation not correct?

Accepted Answer

The reaction is not reversible, because lead chloride is not soluble in water. Reactions must occur in the same phase, and generally only occur in the aqueous or gas phases. There is a small amount of reaction that can occur between the aqueous and solid phases, but it progresses extremely slowly!

Question 19

Which of the following is not a positively charged ion in its natural state?

Accepted Answer

Oxygen is not positively charged in its natural state, and is instead negatively charged. Oxygen is normally found as O^-2, as indicated by its position on the periodic table.

Question 20

The periodic table is a very handy tool, and can be used to predict the properties of the different elements. Which of these rules is not a general rule that can be used to predict properties of elements from the periodic table?

Accepted Answer

The reactivity of elements is not governed by a direct rule in the periodic table. Typically, elements on the left and right edges of the periodic table (with the exception of the noble gases) are very reactive. However, some elements in the middle, such as zinc or iron, are also quite reactive, so this is not a good general rule either.

Quiz 24: Major Ideas