science exam

The Law of Conservation of Mass is satisfied in a chemical reaction when... *

...the reactant side has the same number of each type of atom as the product side

Carla rode her bicycle in a 600 km race heading north toward the finish line. It took her 4 hours to complete the race. What was her average velocity? Velocity = Distance/Time, v=d/t *

150 km per hour north

Magnesium has 2 Valence Electrons in its outer energy level. What charge is magnesium likely to acquire? *

2+

A net force of 15 N causes a shopping cart to accelerate at a rate of 5 m/sec². According to Newton's Second Law of Motion, F=ma, what is the mass of the moving cart? *

3 kg

Convert the following measurement to the correct unit. 3.45 L =________mL

3450 mL

Vinnie leaves on a train from Duncan, SC and travels toward the seaside resort of Myrtle Beach on the Atlantic Ocean. The velocity for the first few seconds of travel is indicated below. Assuming constant acceleration, what would the velocity be after 7 seconds of travel? *

35 m/s East

An atom has 51 electrons. How many total energy levels do its electrons occupy? *

5

Which of the following is the best example of velocity? *

8.6 m/s South

The type of radioactive particle that can be stopped by a sheet of paper is the_______. *

Alpha Particle

Which of the following is the best definition or a radioactive element's half-life? *

Amount of time it takes for half of the nucleus to decay.

Barium has 2 Valence electrons and fluorine has 7. Which of the following would be the correct chemical formula for the stable bond compound Barium Fluoride? *

BaF₂

Which of the following would be the correct chemical name for the formula Be3N2? *

Beryllium Nitride

When a block of sugar is added to water, it will eventually dissolve. If Toby want to increase the rate at which the sugar dissolves, which of the following conditions will be most effective? *

Break the sugar into small pieces to increase the amount of interactions between sugar and water

An organic chemist often works with petroleum and wood products. Which of the following is an organic compound that this chemist might use on a daily basis? *

CH₄

Ionic bonds form between a metal/non-metal and tend to have a crystalline shape. Which of the following is an ionic bond? *

CaCl₂

Carbon-12 and Carbon-14 have the same atomic number but different atomic masses. What else is true about Carbon-12 and Carbon-14? *

Carbon-12 and Carbon-14 are isotopes

Which of the following best describes the process of covalent bonding? *

Covalent bonding is the process of providing chemical stability through sharing of electrons between atoms

The line graph below shows the results of the first day of temperature data collection for a particular city. What conclusion can be made about the graph? *

During the time period tested, the temperatures never vary by more than 20 degrees Fahrenheit

When you activate an instant cold pack water mixes with a chemical named ammonium nitrate to get very cold. Which type of chemical reaction does this involve? *

Endothermic reaction

Which of the following is the most accurate regarding fission and fusion? *

Energy released during fusion is a result of combining two smaller atoms to form one larger atom

Which statement best describes the principle that governs the movement of rockets? *

For every action there is an opposite and equal reaction.

If there is ever a need to smell a chemical in a laboratory, which is the best method to use? *

Hold the flask away from your nose and waft the vapors toward you

How do you determine the oxidation number of an element in a compound? *

Ionic Charge

What unit is used to measure Force? *

Meters/Second²

What particle is needed to complete the nuclear reaction below? *

Neutron

Which pair represents a correct match? *

Neutron; No charge

An unknown aqueous solution is tested with the three pH indicators shown in the table below. The solution turned blue when tested with Bromothymol blue and yellow when tested with both Methyl red and Methyl orange. The investigator concluded that the solution was neutral. Is this a valid conclusion? *

No; because the solution could also be basic

Combining nitrogen and hydrogen gas under high pressure and temperature can make a chemical reaction take place. Which of the following chemical equations is balanced? *

N₂ + 3H₂ -> 2(NH₃)

Balanced forces are equal in size and ______ in direction. *

Opposite

What must a scientist do prior to generating a hypothesis? *

Research information using credible, accurate sources

What is the correct formula for Sulfur Trioxide? *

SO3

Salt lowers the freezing point of water. Which is most likely an application of salt based on this property? *

Salt is often used to melt the ice on roadways

The graph below shows how water changes from a solid to a liquid and then to a gas. What conclusions can most likely be made about energy? *

The addition of heat energy does not always result in a change in temperature

Salt (NaCl) dissolves into its component parts in water (H₂O) as shown below. What statement is represented in the process? *

The positive and negative ions separate when dissolved in water.

The overall winner of the auto race graphed his distance covered over time. Which conclusion can be made about the graph? *

The rate of speed was greatest between the 2nd and 3rd minute of the race.

Acceleration due to gravity on Earth is 9.8 m/sec². A watermelon is dropped from the roof of a building and hits the ground after 5 seconds. How does the acceleration affect the velocity of the falling watermelon? *

The velocity of the watermelon increases each second as it drops to the ground

Student groups were comparing their lab results. All lab groups reported basically the same reaction times except for Jessica and Aaron, whose reaction rates were significantly faster. Which is the most likely explanation for their faster reaction rates? *

They had a greater volume of solution than the other groups

Vinegar is a dilute solution of acetic acid. Which of the following is most likely a chemical property of vinegar? Use the pH scale below to help you answer the question. *

Vinegar has a pH of 6.25

A graduated cylinder is being used to measure a quantity of liquid, as shown in he diagram below. What is the most accurate description of the measurement being taken? *

Volume: 43 milliliters

Which of the following statements is correct about water? *

Water is a molecule composed of hydrogen and oxygen atoms.

Which element is pictured? *

flourine

Shania wanted to see if eating apples would help her do better on her classwork. The first day, she didn't eat any apples. On day 2, she ate one apple; on day 3, she ate 2 apples; and on day 4, she ate 3 apples. Each day, she recorded the grades she got on her science work. What is the dependent variable? *

grades

Which of the element groups listed would be the most stable based on the number of valence electrons they possess? *

group 18

Both nuclear fusion reactions and nuclear fission reactions _________. *

produce energy

If an atom has a neutral charge, what is the number of electrons the same as? *

protons

In which state of matter are the particles closest together? *

solid

Sound is a type of energy transfer. The table below shows the speed of sound through a number of materials. Which statement is supported by this table?

sound travels fastest through solids

An atom of aluminum contains 13 protons and its atomic mass is 27. Which of the following is accurate about aluminum? *

there are 14 neutrons in its nucleus

Evan wanted to find out what toothpaste made teeth the cleanest. Every day he brushed his teeth with a different product and then took a plaque test to see how much plaque was left. He used Crest, Colgate, Close-up, and water. What is the independent variable?

toothpaste

Which of the following illustrates a physical change? *

water freezing