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30 questions
Some students are using samples of different substances for a lab investigation. They plan to observe the physical properties of each substance and record their observations in a table like the one below. Which of the substances observed are elements?
S, Fe, O, Sr, and Al
S, O, and LiF
NO, O,and LiF
NO,Fe,Sr,and Al
Element R and Element Q have the same number of valence electrons. These elements both have similar chemical behavior, but Element R has fewer energy levels than Element Q. Which statement best describes the positions of the two elements in the periodic table?
The two elements are in the same period, with Element R the first element in the period and Element Q the last element.
The two elements are side by side in the same period, with Element Q to the left of Element R.
The two elements are in the same group, with Element R just above Element Q.
The two elements are in the same group, with Element Q at the top of the group and Element R at the bottom.
A student obtains two strips of magnesium, Mg, ribbon that are each 3 cm long. One strip of magnesium is placed in a test tube containing 5 mL of water, and the other strip is placed in a test tube containing 5 mL of hydrochloric acid, HCl. Both liquids are at room temperature. The student’s observations are recorded in the table. Which statement is not supported by the student’s observations?
A chemical reaction takes place between magnesium and hydrochloric acid.
A gas is released in Test Tube 2.
The substances in both test tubes are reactive only at high temperatures.
Energy is released in the reaction involving hydrochloric acid.
What is the difference between the number of electrons in an atom of selenium, Se, and the number of electrons in an atom of aluminum, Al?
21
3
51.989
105.953
Four students were given a list of compounds and asked to identify which ones are organic. Which student correctly identified the organic compounds in the list?
Student K
Student L
Student M
Student N
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. Which student’s responses are correct?
Student 1
Student 2
Student 3
Student 4
Strontium phosphate, Sr3(PO4)2 is a crystalline substance used in medicine and industry. How 42 many phosphorus atoms are represented in the formula for
Sr3(PO4)2?
?
2
3
4
8
chemical reaction in which calcium carbonate, CaCO3, is decomposed results in the production of two simpler compounds. What mass of calcium carbonate, to the nearest hundredth of a gram, is decomposed in this reaction?
21.97g
28.00g
49.97g
6.03g
Students in a science class prepared flashcards so that they could quiz one another about the arrangement of the periodic table. One of the flashcards contained information about two elements, Element L and Element M. The students had to use the information on the flashcard to determine possible positions of the two elements on a blank periodic table. Which periodic table has the elements placed in locations that match the information on the flashcard?
Nitrogen dioxide is a gas that can be generated by emissions from vehicles and factories. It can also be generated by natural sources, such as forest fires, lightning, and microbial activity in soil. The equation for producing nitrogen dioxide is shown below. Which of these provides evidence that a chemical reaction occurs?
A gas is present.
The total number of atoms remains unchanged.
The state of matter remains the same.
A brown gas is produced.
How many protons, neutrons, and electrons are present in an atom of hafnium, Hf, with a mass number of 178?
72 protons, 178 neutrons, 106 electrons
72 protons, 106 neutrons, 72 electrons
178 protons, 250 neutrons, 72 electrons
106 protons, 72 neutrons, 106 electrons
The table shows the chemical formulas for four substances. Which substances have the same number of carbon atoms?
Substances 1 and 2
Substances 2, 3, and 4
Substances 2 and 3 only
Substances 1 and 3
Tin, Sn, is a soft white metal. It has a low melting point compared with other metals. Tin is widely used as a coating for cans of food. Which statement accurately describes atoms of tin?
Tin atoms have 50 protons.
Tin atoms have five valence electrons.
Tin atoms have 119 neutrons.
Tin atoms have 68 electrons.
A balance and a graduated cylinder are used to determine the density of a mineral sample. The sample has a mass of 14.7g and a volume of 2.2cm3 .What is the density of the
mineral sample?
0.15 g/cm3
32 g/cm3
13 g/cm3
6.7 g/cm3
A researcher wants to experiment with an element that reacts like phosphorus (P) but has a greater atomic mass. Which element should the researcher select for the experiment?
Nitrogen (N)
Sulfur (S)
Arsenic (As)
Silicon (Si)
A model of an atom is shown. An atom of which element is represented by this model?
Boron (B)
Carbon (C)
Neon (Ne)
Sodium (Na)
Which of the following best describes an electron?
It has no charge and about the same mass as a proton.
It has a negative charge and much less mass than a proton.
It has a positive charge and much more mass than a neutron.
It has a negative charge and about the same mass as a neutron.
A scientist spilled a few drops of dilute hydrochloric acid (HCl) on a lab table. For safety purposes, the scientist sprinkled some baking soda (NaHCO3) onto the spill. Which observation would provide the best evidence that a chemical reaction occurred?
The baking soda and hydrochloric acid combined, and bubbles formed.
The baking soda absorbed the hydrochloric acid.
Some of the baking soda dissolved in the hydrochloric acid.
The hydrochloric acid evaporated, leaving only the baking soda.
Which information could a student determine from only the chemical formula of a protein?
The color of the protein
The number of molecules in each sequence that makes up a protein
The physical arrangement of atoms in the structure of the protein
The number of atoms of each element in the protein
A teacher asks a student to write the chemical equation for photosynthesis. The student’s response is shown below. The equation is not balanced correctly. Which of these is a balanced equation for photosynthesis?
When trying to identify an unknown element, a scientist determines what other elements the unknown element reacts with chemically. Which property of the unknown element determines the other elements it reacts with?
The total number of neutrons in the unknown element
The total number of particles in the nuckleus of the unknown element
The number of protons in the nucleus of the unknown element
The number of valence electrons in the unknown wlwment
The model of the periodic table below shows the locations of four elements. A student is asked to identify an element that is a pale-yellow brittle solid and does not conduct electricity. At which location in this periodic table would the element most likely be found?
1
2
3
4
An atom has 25 protorn, 30 neutrons, and 25 electrons. What is the charge of the atom's nucleus?
+25
+30
-25
-30
How many atoms of oxygen are in a molecule of glucose (C6H12O6)
6
12
24
3
The chemical equation shown below represents a reaction that produces fuel for certain cars.
CO + H2O ---> CO2 +H2
Which substance represented in this equation is classified as an element?
CO
H2O
CO2
H2
During an investigation, a student combined the two clear, colorless solutions shown below. The student observed that the temperature changed from 25°C to 23°C when the solutions were combined and that a white substance rapidly formed and settled to the bottom of the container. What most likely happened to produce these results?
One of the orginal compounds came out of solution
The solutions reacted chemically
Some of the water frose into ice crystals
Rapid evaporation of water occurred, leaving a solid
Coal contains carbon and other elements. Carbon dioxide forms when coal burns in the presence of oxygen. Which of these is the best evidence that a chemical reaction occurs when coal burns?
The shape of the coal changes
Oxygen is present
A new substance is produced
Coal is made up of more that one element
The atoms of a certain element each contain 11 protons and 1 valence electron. Which statement correctly identifies this element and describes its chemical reactivity?
The element is sodium, and it is highly reactive
The element is fluorine, and is not very reactive
The element is sodium, and it is not very reactive
The element is fluorine, and it is highly reactive
An atom of a certain element has 36 protons, 36 electrons, and a mass number of 84. At room temperature this element is a very stable gas. How many neutrons are in this atom?
36
84
48
72
All the following reactions are correctly balanced except—
2C2H2 + 5O2 ---> 4CO2 + 2H2O
4Fe +3O2 ---> 2Fe2O3
NaHCO3 ---> Na2CO3 + H3O + CO3
2CH3OH + 3O2 ---> 2CO2 + 4H2O
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