Chemistry 1 / mid-term

Beta Decay of Americium

B. 16 hours

The drawing shows a model of moving gas molecules in a closed container. The longer the length of each arrow indicates the relative speed of each gas molecule has increased.

B. An increase in temperature resulting from an increase in the average kinetic energy of the gas molecules.

Which statement describes a nuclear reaction?

B. Atoms of hydrogen combine to form an atom of helium.

Which of the samples below would have a higher temperature?

B. B ( going out )

The table shows three different types of nuclear reactions. Which of these correctly identifies each of the nuclear reactions?

D. 1 decay, 2 fission, 3 fusion

The diagram below shows the setup and results of Ernest Rutherford's gold foil experiment

D. A small, positive nucleus in mostly empty space

Jane compiled a list of physical and chemical changes of a sample of matter, as shown below. Which four numbers on the list indicate only physical changes?

A. 1,2,6,7

A student does an experiment to see if adding sugar to water affects how long it takes the water to boil. Using the data in the table, what can we infer about the effect of sugar on the boiling time of water?

A. Adding sugar increases the time for the water to boil

Science is always concerned about information and knowledge about the physical world around us. Phosphorus is a chemical element that was discovered in the 1600s, and since then much has been found about phosphorus. Some of the information about phosphorus is listed below. Which statement best describes what can be said about this information that has been discovered about phosphorus?

A. Any observations about phosphorus are still open to change as new evidence is discovered.

The table shows four comments. The comments are about either nuclear reactions or chemical reactions. Which comments correctly describe these reactions?

A. Comments 1 and 2

The graph below shows atmospheric carbon dioxide over the last 50 years. The data comes from recordings taken at Mauna Loa, Hawaii by scientists at Scripps Institution of Oceanography. Which of the following statements is most reasonable?

A. The data is reliable because it follows the rules of scientific method

Nuclear fission is a process that has been around for more than 50 years. Why does there continue to be public concern regarding nuclear power plants?

A. The waste from the fission reaction is radioactive.

In the chemical reaction represented by the energy diagram below, reactants A and B react to form products C and D. Which statement describes the reaction?

A. a. The reaction is exothermic and release energy

A student reads an article about a geologist performing an X-ray fluorescence experiment to determine the chemical composition of samples of igneous rocks. The percent error of the X-ray fluorescence instrument is +/- 0.2%. Which aspect of the research indicates the reliability of the paper?

A. choice of instrument

The diagram below represents one of the hallmark experiments on the development of the atomic theory. Which particle in an atom did this experiment help discover?

A. electron

Both fission and fusion are nuclear reactions, but only one process results in radioactive decay. Which process does, and why?

A. fission - the nucleus is unstable

A student causes a reaction between vinegar and sodium bicarbonate. The reaction produces carbon dioxide gas, sodium acetate, and water. The student measures reactants and products throughout the experiment. Which step would be an appropriate part of a scientific experiment that uses SI units?

A. pouring 50 mL of vinegar into a glass beaker

For her science fair project, Samantha would like to see how different substances affect bone mass. She collects several chicken leg bones from the grocery store, records each bone's mass, and soaks them in different liquids for 48 hours. After 48 hours Samantha measures the mass of each bone again. Below is a data chart of Samantha's experiment. Based on the data, which liquid caused the most bone loss?

B. Diet Soda

The graph below shows the data a student collects for an investigation. Two moles of solute were dissolved in water in both cases. Which of the following questions can be answered based on the data collected?

B. How do sugar and salt affect the freezing point of water?

Students are going to conduct an experiment to determine the strength of hydrogen bonds in different liquids: water and alcohol. The students will drop each liquid onto the surface of a penny and count the number of drops until the liquid spills off. Which of the following would be an appropriate hypothesis for this experiment?

B. If the liquid has strong hydrogen bonds, the number of drops the penny can hold will be higher than the ones with no hydrogen bonds

Antoine Lavoisier discovered the relationship between the mass of reactants and products. Which statement best explains how this discovery became a scientific law?

B. Many scientists were able to demonstrate the same relationship

The diagrams show two different atomic models .

B. They both distinguish the nucleus from the rest of the atom.

Two models used in chemistry are shown below.

B. To provide concrete ideas about microscopic structures

The graph below shows the distribution of molecular speeds in a sample of a gas. Which change would cause the peak of this curve to shift to the right?

B. an increase in temperature

Lindsay is working with a sample that can easily be manipulated into different states of matter. She is carefully recording her observations about how the sample changes into a different state. What would be the key observation for Lindsay to make regarding when the sample changes into a different state of matter?

B. change in temperature

A student is seeking information on the effects of a chemical spray on a wildflower species. Which resource should the student use to scientifically determine the chemical's effects?

B. data from a controlled experiment using the chemical on the wildflowers

In an exothermic chemical or physical change, the temperature of the surroundings would

B. increase due to a loss of energy

Beginning in the middle of the eighteenth century, various scientists proposed several models of atomic structure. In the nineteenth and early twentieth centuries a number of elegant experiments tested these models and laid the foundation of modern atomic theory. Which table correctly presents the scientists who made significant contributions to modern atomic theory?

C. ( energy levels )

The diagram below shows J.J. Thomson's early model of the atom. This model was later revised to include an important experimental observation. Which observation led to the revision of Thomson's model?

C. Electrons are only observed at certain distances from the nucleus.

The modern atomic theory is called the cloud model. What does the cloud consist of?

C. Electrons moving in random directions in an energy level

Three kinds of nuclear reactions release energy. What is the correct order of nuclear reactions from least amount of energy released to most energy released?

C. Radioactive decay, fission, fusion

A research team conducted an investigation to establish the relationship between the concentration of a new pesticide and the health impact of the pesticide on developing fish eggs. The team populated five tanks each with 500 fish eggs in water containing a different pesticide concentration. The number of fish eggs that developed normally in each tank and the pesticide concentrations are shown in the data table below. Which of the following would improve the experimental design of this investigation?

C. Repeating the investigation with additional concentration levels between 0 M and 0.50 M

The table below lists observations from different experiments conducted on four different samples of matter. Each sample was kept in a closed container. Which sample is behaving like a gas?

C. Sample 3

Two groups of students performed tests to identify an unknown solution. The first group mixed the solution with baking soda. The second group heated the solution. The students recorded their results in the table below. What can the students conclude about the unknown solution?

C. The appearance of bubbles in Group 1's experiment indicates that a chemical change occurred.

Georgina is examining two equations and trying to determine the difference between the two reactions that release energy. They both involve the same elements and compounds. Both equations are properly balanced. She notices that one equation also involves atomic numbers and mass numbers. Based upon this information, which of the following statements is true?

C. The equation with mass numbers and atomic numbers is a nuclear reaction, while the other is a chemical reaction.

An atom contains 3 protons, 3 electrons, and 4 neutrons. Which of the following statements correctly describes the nucleus of this atom?

C. The nucleus contains 3 positively charged particles and 4 neutrally charged particles

Three students measured the mass of a piece of copper. The results recorded by the students were 42.7 grams, 42.5 grams, and 42.6 grams. The actual mass of the copper was 41.0 grams. Comparing the student results with the actual value, how would you describe their accuracy and precision?

C. low accuracy, high precision

The following graph shows the kinetic energy distribution of the molecules of a pure gas. If this is an ideal gas, which difference between the molecules could explain the distribution of their kinetic energies?

C. their varying temperatures

In a laboratory activity, a student first observed and collected the data of three beakers each filled with 50-ml of water. The water's temperature and student's observations were recorded as shown. Next, the student added two drops of food coloring at room temperature by holding the dropper 6 cm above each beaker. The water in beaker A mixed the food coloring rapidly and was recorded as mixing first. The two drops of food coloring added to beakers B and C went directly to the bottom of the beaker and spread out without mixing. Which statement supports the student's observation and reasoning about which beaker's food coloring will mix in the 50-ml of water next?

D. Beaker C will mix next because the molecules of beaker C will gain heat energy and warm.

English chemist John Newlands organized elements in rows of eight. Russian chemist Dmitri Mendeleev improved on this idea by leaving gaps in the periodic table for unknown elements. Scientists then discovered elements that Dmitri Mendeleev's table predicted. One result of this work was the development of the atomic theory. How does this work on the periodic table best show the development of scientific theory?

D. Evidence from other investigations validates theories

Which statement best compares the two chemical reactions shown above?

D. One reaction is endothermic and exothermic

A group of scientists collected data to measure how water density changes with water temperature. The data collected is in the table below. Which type of graph should the experimenters use to best analyze this data?

D. Scatter plot

In nuclear reactions, which of the following occurs?

D. Small amounts of mass are converted to large amounts of energy.

A diagram of an atom with a part labeled Particle X is shown below

D. Small mass and negative charge

The temperature of two samples of rubbing alcohol is taken. Sample 1 has a temperature of 20ºC and Sample 2 has a temperature of 30ºC. Which statement best describes the reason for the different temperatures of the two samples?

D. The particles in Sample 2 have more kinetic

The diagram below represents the potential energy for a chemical reaction.

D. This is an endothermic reaction because energy was absorbed

in 400 BC, Democritus first proposed the idea of an atom. In the 1800s, Dalton's experiments added five key points about the atom. Thomson's experiments refined the model Dalton proposed about the atom. In the 1900s, Rutherford, Bohr, and Chadwick contributed more knowledge about the atom through experimentations making more changes to the model. When compiled together, what does this mean?

D. When scientists compile their results about the atom, it builds validity that establishes a theory.

The diagram below shows the different phases of water at the molecular level. Which list identifies the states of matter shown in this diagram?

D. X: gas Y liquid Z solid

One of the early models proposed for an atom was the idea that electrons were scattered around a positively charged environment. This model has changed significantly over time. What resulted from these changes?

D. acceptance of the valence shell electron pair repulsion (VSEPR) theory

Compared to chemical reactions, nuclear reactions produce

D. far less energy