General Science Praxis Practice Exam

Which of the following guidelines should be used when collecting data during an experiment?

a. Vary only one factor at a time when studying how a system responds.

b. Take all measurements at the same time.

c. Make sure that the measurements agree with the hypothesis that motivated the experiment.

d. Make sure the measurements form a straight line when plotted on a graph.

Which of the following is equivalent to 1 × 10-3 gone times 10 to the negative 3 grams?

a. 0.0001 gram

b. 1 kilogram

c. 1 milligram

d. 100 micrograms

Which of the following characteristics is most important in demonstrating that a hypothesis should be called a theory?

a. It interprets an observation.

b. It states a conclusion supported by an experiment.

c. It summarizes the most recent work of a scientist.

d. It provides an explanation for the results of many experiments.

Jar 1: Open to air

Jar 2: Opening of the jar tightly closed

Jar 3: Opening of jar covered with fine mesh

In an attempt to disprove the belief that living things, such as maggots, can originate spontaneously from decaying meat, fresh meat was placed in jars as shown above. The hypothesis that flies are the source of maggots that appear on decaying meat would best be supported if maggots are later found in which jar?

a. 1 only

b. 2 only

c. 3 only

d. 1 and 3

A thermometer inserted into a solution has a mercury level of just a bit less than halfway between the markings for 22.4º C and 22.5º C. To represent the correct number of significant figures, the temperature of the solution should be recorded as

a. 22

b. 22.4

c. 22.44

d. 22.5

Experimental evidence supports the fact that most of the mass of an atom is contained in which of the following?

a. The electron cloud

b. The nucleus

c. The sublevels

d. The valence level

A student placed 20 radish seeds on a damp paper towel in a petri dish and placed the dish under a fluorescent light. After 48 hours, all the seeds had germinated. In order for the student to draw a valid conclusion about the effect of water on seed germination, which of the following should also have been included in the investigation?

a. A second dish should have been placed in the dark.

b. A second dish should have been placed in a refrigerator.

c. A second dish with a dry, rather than damp, paper towel should have been used.

d. A second dish with a dry, rather than damp, paper towel should have been placed in direct sunlight on a windowsill.

Which of the following will result in a solution of 0.50 M HClzero point five zero molar H C l ?

a. 250 mL of 2.0 M HCl added to 750 mL H2O

b. 500 mL of 1.0 M HCl added to 1,000 mL H2O

c. 100 mL of 0.50 M HCl added to 900 mL H2O

d. 200 mL of 0.10 M HCl added to 1,000 mL H2O

The height to which a ball bounces is compared to the height from which it is dropped. The ball is dropped from five different heights, and the results are plotted above. On the basis of these data, it should be concluded that the

A: height of the bounce is directly proportional to the height of the drop

B: height of the bounce is inversely proportional to the height of the drop

C: data point for the 6-foot drop does not seem to fit the pattern and the drop should be repeated

D: data points for the 8-foot drop and the 10-foot drop do not seem to fit the pattern and the drops should be repeated

Which TWO of the following are appropriate laboratory safety standards?

a. An emergency shower is located within a travel time of 10 seconds.

b. Prescription eyeglasses provide sufficient eye protection.

c. Short pants are proper laboratory attire.

d. Closed-toe shoes should always be worn.

The number of sunspots on the surface of the Sun increases and decreases over an 11-year period called the solar cycle. The graph above shows how the number of sunspots varied over 50 years. When will the next minimum and the next maximum in the number of sunspots most likely occur?

Minimum Maximum

2004 2015

2006 2008

2007 2011

2009 2014

Which of the following parts of a compound microscope would be used to regulate the amount of light transmitted through the specimen on a slide?

a. Diaphragm

b. Nosepiece

c. Fine adjustment knob

d. Coarse adjustment knob

Four experiments were done with a metal wire. In each experiment, the resistance of the wire at a low and a high temperature was measured more than once. Which experiment gives the strongest evidence that resistance increases as temperature increases?

RESISTANCE (ohms) RESISTANCE (ohms)

Low Temperature High Temperature

600 K 800 K

Experiment 1 4.1 4.4

4.4 4.1

Experiment 2 4.2 4.4

4.3 4.5

Experiment 3 4.0 4.5

4.0 4.5

4.1 4.4

4.0 4.5

Experiment 4 4.3 4.3

4.2 4.4

4.0 4.2

4.2 4.2

Experiment 1

Experiment 2

Experiment 3

Experiment 4

Which of the following is a safe laboratory procedure?

a. Preparing a dilute acid solution by adding a small amount of concentrated acid to water in a flask

b. Using a flame to heat an open beaker of alcohol

c. Storing volatile liquids in containers with loose lids

d. Flushing all waste chemicals down the laboratory sink with large amounts of water

Johannes Kepler's greatest contribution to science was that he

a. proposed the law of universal gravitation

b. discovered the first radioactive element

c. described the orbits of the planets as ellipses

d. developed the microscope

One similarity between the Bohr and quantum mechanical models of the atom is that electrons

a. are embedded in the nucleus

b. revolve around the nucleus in circular orbits

c. are only in certain allowed energy states

d. behave as particles and not as waves

When a log burns in a fireplace, producing ash and smoke, which of the following is true?

a. Energy is created but matter is conserved.

b. Energy is created and matter is destroyed.

c. Energy is conserved but matter is destroyed.

d. Energy and matter are both conserved.

The change in Gibbs energy for a reaction at constant temperature is given by the equation above. For an endothermic reaction with ΔH = +20,000 Jchange in enthalpy equals positive 20,000 joules and ΔS = +100 J/Kchange in entropy equals positive 100 joules per kelvin, which of the following is true about the reaction?

a. It is never spontaneous.

b. It is always spontaneous at any temperature.

c. It is spontaneous at temperatures above 200 K200 kelvins only.

d. It is spontaneous at temperatures below 200 K200 kelvins only.

During a chemical process, a system absorbs 4.8 kJ4 point 8 kilojoules of heat while doing 1.2 kJone point 2 kilojoules of work on the surroundings. The change in internal energy of the system is

a. +4.8 kJ

b. +3.6 kJ

c. -1.2 kJ

d. -6.0 kJ

Which of the following is the ground state electron configuration for TiT i?

a. 1s22s22p23s23p64s2

b. 1s22s22p63s23p64s24p2

c. 1s22s22p63s23p63d4

d. 1s22s22p63s23p64s23d2

If a beaker and a bathtub are each filled with pure boiling water, which of the following indicates the relative temperatures and heat content of the water in each?

Temperature Heat Content

Higher in bathtub Greater in bathtub

Higher in beaker Greater in beaker

Same in both Same in both

Same in both Greater in bathtub

Which of the following is formed when a beta particle is emitted from sodium-24, as shown above?

Mg 12

24

Na 11

23

Ne 10

24

F 9

20

When a substance undergoes a phase change from a gas to liquid at its boiling point, which of the following properties of the substance always decreases?

Density

Mass

Temperature

Entropy

In cold weather, it is more difficult to make people comfortable in a room with a high ceiling than in a room with a low ceiling primarily because

a. cold air is more dense than warm air

b. humid air is more dense than dry air

c. convection currents do not occur in rooms with a high ceiling

d. evaporation occurs more rapidly in a room with a high ceiling than in a room with a low ceiling

Which of the following properties of matter refers to the ability to be hammered into thin sheets?

a. Density

b. Tensile strength

c. Malleability

d. Ductility

A sample contains 8 g of a radioisotope that has a half-life of 10 years. How much time is required for the sample to decay until approximately 1 gone gram of the isotope remains in the sample?

10 years

30 years

80 years

800 years

An alkaline battery converts which of the following forms of energy into electrical energy?

Heat

Kinetic

Chemical

Mechanical

A sample of liquid water of a certain mass at 20°C and 1 atm20 degrees Celsius and one atmosphere has a volume of 1,000 mL1,000 milliliters. Which of the following is the most likely volume of a water sample with the same mass at 80°C and 1 atm80 degrees Celsius and one atmosphere?

a. 970 mL

b. 1,000 mL

c. 1,027 mL

d. 4,000 mL

Based on the graph above of a vehicle's progress along a highway, which of the following is true for the car?

a. It has the same speed at 5 minutes and at 55 minutes.

b. It has the highest acceleration in the time interval 0-5zero to five minutes.

c. It stopped for 20 minutes.

d. It traveled downhill for 5 minutes halfway through the trip.

For which of the following positive charges, separated by the distances shown, will the electrostatic force of repulsion be smallest?

True statements about simple machines include which THREE of the following?

a. A simple machine makes the work required to perform a task easier.

b. A simple machine reduces the total amount of work required to perform a task.

c. A simple machine can change the magnitude or direction of a force.

d. The mechanical advantage of a simple machine is the amount by which the machine multiplies the input force

In which of the following are the types of electromagnetic radiation listed in order of increasing energy?

a. Visible < infrared < gamma rays < ultraviolet

b. Infrared < visible < ultraviolet < gamma rays

c. Gamma rays < visible < infrared < ultraviolet

d. Ultraviolet < visible < infrared < gamma rays

A ball is thrown in a horizontal direction. The ball is released at a vertical height of 6 feet and with an initial speed along the horizontal direction only, as shown in figure IRoman numeral 1. At the same time, an identical ball is dropped from rest from a vertical height of 6 feet, as shown in figure IIRoman numeral 2. Which of the following best describes what happens subsequently? (Assume that air friction is negligible)

a. The thrown ball will hit the ground first because it is moving with a greater speed.

b. The thrown ball will hit the ground first because it has a greater acceleration.

c. The dropped ball will hit the ground first because it has a shorter distance to travel.

d. Both balls will hit the ground at the same time.

If a wire carries a steady current of 0.1 ampzero point one ampere for 20 seconds, which of the following gives the total charge passing through the wire during this time interval?

a. 0.005 coulomb

b. 2 coulombs

c. 20 coulombs

d. 200 coulombs

A 10 kg10 kilogram cart is rolling along the surface shown in the figure above. What is the minimum kinetic energy of the cart at the base of the hill if it is going to be able to roll to the top of the upper level? (Assume g = 10 m/s2 g equals, 10 meters per second squared.)

a. 4 joules

b. 10 joules

c. 40 joules

d. 400 joules

The distance between the adjacent nodes of a one-dimensional standing wave is 0.500 mzero point five zero zero meter. If the frequency of the wave is 100.0 Hz100 point zero hertz, then the speed of the wave is

a. 25.0 m/s

b. 50.0 m/s

c. 100.0 m/s

d. 200.0 m/s

Two astronauts, of masses 60 kg60 kilograms and 80 kg80 kilograms, are initially at rest in outer space. They push each other apart. If the speed of the lighter astronaut is 12 m/s12 meters per second, what is the speed of the heavier astronaut?

a. 4 m/s

b. 9 m/s

c. 12 m/s

d. 16 m/s

The device shown above has an input voltage of 25.0 V and an output voltage of 50.0 V. The device is which of the following?

a. Resistor

b. Capacitor

c. Battery

d. Transformer

The spring shown above stretches 3 cm3 centimeters when a mass of 4 kg4 kilograms is suspended from it. How far would this spring stretch if a 12 kg12 kilograms mass were suspended from the spring in place of the 4 kg4 kilograms mass? (Assume that the elastic limit is not reached.)

a. 4 cm

b. 6 cm

c. 9 cm

d. 11 cm

If a flat object is placed 3 meters in front of a plane mirror, the image will be formed

a. on the surface of the mirror

b. 3 meters behind the surface of the mirror

c. greater than 3 meters behind the surface of the mirror

d. less than 3 meters behind the surface of the mirror

A tractor is pulling a wagon full of hay. The mass of the wagon and hay is two times the mass of the tractor. When the tractor accelerates forward, the force that the wagon exerts on the tractor is

a. two times greater in magnitude than the force that the tractor exerts on the wagon

b. equal in magnitude to the force that the tractor exerts on the wagon

c. one-half the magnitude of the force that the tractor exerts on the wagon

d. zero, since the tractor is pulling the wagon forward

A tractor is pulling a wagon full of hay. The mass of the wagon and hay is two times the mass of the tractor. When the tractor accelerates forward, the force that the wagon exerts on the tractor is

a. two times greater in magnitude than the force that the tractor exerts on the wagon

b. equal in magnitude to the force that the tractor exerts on the wagon

c. one-half the magnitude of the force that the tractor exerts on the wagon

d. zero, since the tractor is pulling the wagon forward

Which of the following combinations of identical resistors produces the smallest total resistance?

If the length of a simple pendulum is doubled, the period of the pendulum will

increase by a factor of 2

increase of a factor by 2√

the square root of 2

remain the same

decrease by a factor of 2