Pre-test questions Study Guide Rated A+
indpendent variable
Control
A chemist made the table below to record some atomic properties of four elements.Based on the information in the table, which conclusion about the chemical reactivity of these elements is valid?
Based on these drawings, which e...
Ans: the experimental factor that is manipulated; the variable whose affect is being
studied
2). Control
Ans: In an experiment, the standard that is used for comparison
3). A chemist made the table below to record some atomic properties of four elements.based
on the information in the table, which conclusion about the chemical reactivity of these
elements is valid?
Ans: Fluorine is the most reactive because it has 7 electrons in the outer shell.
4). Based on these drawings, which element is the least reactive?
Ans: Neon, because it has two energy levels with eight elections
5). Four students were asked to name the parts of an atom that determine the atom's identity
and chemical properties. the students' responses are shown in the table below.
Ans: Student 2
6). A chemist is identifying the elements present in a sample of seawater. what characteristic
of an elements atom always determines the element's identity?
Ans: The number of protons
7). A scientist performs tests on a a sample of an element. the element is a shiny solid that
conducts electricity and heat. the scientist is able to bend and flatten the sample when
pressure is applied to it. based on this information, the element could not be a member of
which group on the periodic table?
Ans: group 18
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, 8). A compound secreted by honeybees to paralyze intruders in their hive is known as 2-
heptanone. the formula for this compound is shown. ch3 c4 h8 coch3 how many atoms of
each element are in one molecule of 2-heptanone?
1/1
Ans: 7 carbon atoms, 14 hydrogen atoms, and 1 oxygen atom
9). Which statement best describes evidence that a chemical reaction occurs as a cake bakes?
Ans: The cake rises as gas bubbles form in the baking cake.
10). The diagram shows a model of an atom. the model has four different symbols on it. each
symbol represents a different role for one of the particles within the atom.in this model,
which particle determines the reactivity of this atom?
Ans: particle z
11). For a laboratory investigation some students put a strip of shiny metal into a beaker of blue
solution and then stored the beaker on a shelf overnight. the next morning, the students
recorded observations about the metal and the solution in the box below.based on their
observations, can the students correctly conclude that a chemical reaction occurred?
Ans: Yes, because a new material of a different color formed on part of the metal strip
12). As part of an investigation, students combined substances in a beaker to observe chemical
reactions. they performed two procedures. they measured the mass of each substance
before and after each reaction. the table shows their observations. assuming the students
did not make any careless errors, what likely explains these changes in mass?
Ans: Procedure 1: One of the products was a gas that escaped into the air. Procedure
2: A gas from the air reacted with one of the other reactants
13). The mass of an unidentified rock is 15.5 grams. students determine the volume of the rock
by placing the rock in a cylinder with water. the students calculate the density of the rock.
they determine the identity of the rock based on the density ranges in the table. the students
most likely have which type of rock?
Ans: peridotite
14). The net force on a vehicle that is accelerating at a rate of 1.5m/s2 is 1,800 newtons. what is
the mass of the vehicle to the nearest kilogram? (numerical answer)
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