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Worksheets8th Grade Category 1
Total questions: 31
Worksheet time: 5hrs 6mins
Name
Class
Date
1.
(8.5A) An atom has 25 protons, 30 neutrons, and 25 electrons. What is the charge of the atom's nucleus?
a)
+25
b)
+30
c)
-25
d)
-30
2.
(8.5A) Which of these best describes one of the subatomic particles that could be found at location X in the model of an atom shown above?
a)
It has mass but no charge.
b)
It has no mass and a positive charge.
c)
It has a large mass and a negative charge.
d)
It has no mass and an equal number of positive and negative charges.
3.
(8.5B) An atom of which element is represented by this model?
a)
Boron (B)
b)
Carbon (C)
c)
Neon (Ne)
d)
Sodium (Na)
4.
(8.5B) 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?
a)
The total number of neutrons in the unknown element.
b)
The total number of particles in the nucleus of the unknown element
c)
The number of protons in the nucleus of the unknown element
d)
The number of valence electrons in the unknown element.
5.
(8.5C) The periodic table is organized into groups and periods of elements. The characteristics of a certain group of elements are listed below.
-is shiny
-is solid at room temperature
-has atoms with two valence electrons
Which of these elements is in this group?
-is shiny
-is solid at room temperature
-has atoms with two valence electrons
Which of these elements is in this group?
a)
Lithium
b)
Strontium
c)
Aluminum
d)
Silicon
6.
(8.5C) A student is studying the ways different elements are similar to one another. Diagrams of atoms from four different elements are shown below.
Which two atoms are of elements in the same group in the periodic table?
Which two atoms are of elements in the same group in the periodic table?
a)
Atom 1 and Atom 2
b)
Atom 1 and Atom 4
c)
Atom 2 and Atom 3
d)
Atom 3 and Atom 4
7.
(8.5C) A researcher wants to experiment with an element that reacts like phosphorous (P) but has a greater atomic mass. Which element should the researcher select for the experiment?
a)
Nitrogen (N)
b)
Sulfur (S)
c)
Arsenic (As)
d)
Silicon (Si)
8.
(8.5D) The chemical formula for sodium sulfate is Na2SO4. How many sulfur atoms are in the formula for sodium sulfate?
a)
1
b)
2
c)
6
d)
7
9.
(8.5D) Serotonin is a chemical substance that acts as a neurotransmitter. It helps relay messages in the human brain. The formula for one molecule of serotonin is shown below.
C10H12N2O
How may atoms in all are in a molecule of serotonin?
C10H12N2O
How may atoms in all are in a molecule of serotonin?
a)
10
b)
25
c)
24
d)
100
10.
(8.5D) Which information could a student determine from only the chemical formula of a protein?
a)
The color of the protein
b)
The number of molecules in each sequence that makes up a protein
c)
The physical arrangement of atoms in the structure of the protein
d)
The number of atoms of each element in the protein
11.
(8.5E) The scientist spilled a few drops of dilute hydrochloric acid (HCl) on a lab table. For safety purposes, the scientist sprinkled some baking soda (NaCO3) onto the spill. Which observation would provide the best evidence that a chemical reaction occurred?
a)
The baking soda and hydrochloric acid combined, and bubbles formed.
b)
The baking soda absorbed the hydrochloric acid.
c)
Some of the baking soda dissolved in the hydrochloric acid.
d)
The hydrochloric acid evaporated, leaving only the baking soda.
12.
(8.5E)A student observes some sugar as it is heated and burns. The student concludes that a chemical reaction has occurred. Which of the following observations about the burning sugar provides evidence of a chemical reaction?
a)
Heat is added to the sugar crystals.
b)
The sugar melts and becomes a liquid.
c)
The temperature of the sugar increases
d)
Gas is produced as the sugar turns black.
13.
(8.5F) A teacher asks a student to write the chemical equation for photosynthesis. The student's response is shown below
CO2 + H2O ---> C6H12O6 + O2
The equation is not balanced correctly. Which of these is a balanced equation for photosynthesis?
CO2 + H2O ---> C6H12O6 + O2
The equation is not balanced correctly. Which of these is a balanced equation for photosynthesis?
a)
12CO2 + H2O ---> C6H12O6 + O2
b)
CO2 + 9H2O ---> C6H12O6 + O2
c)
CO2 + H2O ---> 3C6H12O6 + O2
d)
6CO2 + 6H2O ---> C6H12O6 + 6O2
14.
(7.5C) The flow of energy in some Australian food chains is modeled in the energy pyramid.
Based on the model, which consumers would receive the greatest amount of energy captured by the producers in their food chains?
Based on the model, which consumers would receive the greatest amount of energy captured by the producers in their food chains?
a)
Wedge-tailed eagles
b)
Chuditch
c)
Ring-tailed opossums
d)
Eucalyptus trees
15.
(7.6A) Hay is made up of organic compounds. What are the main elements in many organic compounds?
a)
Helium, carbon, sodium
b)
Sodium, hydrogen, nitrogen
c)
Carbon, hydrogen, oxygen
d)
Radon, oxygen, helium
16.
(7.6B) Many processes occur in the digestive system. Which process is best classified as a physical change?
a)
Saliva converting starch molecules in crackers to simple sugars
b)
Digestive enzymes breaking down proteins into smaller fragments
c)
Bacteria converting lactose into simple sugars in the intestines
d)
Teeth grinding an almond into smaller pieces in the mouth
17.
CaCO3 ---> CaO + CO2
In the chemical reaction shown above, the products are best classified as-- (6.5C)
In the chemical reaction shown above, the products are best classified as-- (6.5C)
a)
two elements
b)
one element and one compound
c)
two compounds
d)
two compounds and one element
18.
(6.6A) Some students conducted a laboratory investigation to learn more about the physical properties of different elements. They observed four samples and recorded their observations in the table below.
Based on these observations, which sample is most likely a nonmetal?
Based on these observations, which sample is most likely a nonmetal?
a)
Sample 1
b)
Sample 2
c)
Sample 3
d)
Sample 4
19.
(8.5A) In the early 1900s many scientists thought that an atom consisted of a positive substance with negative charges scattered throughout the substance. Then Ernest Rutherford completed an experiment that changed the concept of an atom. His discovery led to the understanding that an atom consists mostly of empty space with-
a)
protons orbiting a dense nucleus made of electrons and neutrons
b)
electrons orbiting a dense nucleus made of protons and neutrons
c)
neutrons and protons orbiting a cloud of electrons
d)
electrons and protons orbiting a cloud of neutrons
20.
(8.5B) 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?
a)
The element is sodium, and it is highly reactive.
b)
The element is flourine, and it is not very reactive.
c)
The element is sodium and it is not very reactive
d)
The element is flourine, and it is highly reactive
21.
(8.5B) A chemist is identifying the elements present in a sample of seawater. What characteristic of an element's atoms always determines the element's identity?
a)
The number of protons
b)
The number of neutrons
c)
The location of valence electrons
d)
The number of valence electrons
22.
(8.5D) In which of these compounds are there twice as many oxygen atoms as hydrogen atoms?
a)
H3PO4
b)
H2SO4
c)
HClO3
d)
H2O
23.
(6.5C) The chemical equation shown below represents a reaction that produces fuel for certain cars.
CO + H2O ---> CO2 + H2
Which of these represents an element?
CO + H2O ---> CO2 + H2
Which of these represents an element?
a)
CO
b)
H2O
c)
CO2
d)
H2
24.
(8.5A) Which of the following best describes an electron?
a)
It has no charge and about the same mass as a proton
b)
It has a negative charge and much less mass than a proton
c)
It has a positive charge and much more mass than a neutron
d)
It has a negative charge and about the same mass as a neutron
25.
(8.5C) Which two elements on the periodic table are in the same period?
a)
Sn and Rb
b)
F and Cl
c)
K and Ba
d)
Se and Te
26.
(8.5D) Which of these formulas contain equal numbers of nitrogen atoms?
a)
Formulas I and III
b)
Formulas I and IV
c)
Formulas II and III
d)
Formulas I, II, and V
27.
(8.5B) 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?
Which of the substances observed are elements?
a)
S, Fe, O, Sr, and AlS, Fe, O, Sr, and Al
b)
S, O, and LiF
c)
NO, O,and LiF
d)
NO,Fe,Sr,and Al
28.
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?
a)
21
b)
12
c)
52
d)
3
29.
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?
Which student correctly identified the organic compounds in the list?
a)
K
b)
L
c)
M
d)
N
30.
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?
Which student’s responses are correct?
a)
1
b)
2
c)
3
d)
4
31.
Strontium phosphate,
Sr3 (PO4)2 is a crystalline substance used in medicine and industry. How many phosphorus atoms are represented in the formula for
Sr3 (PO4 ) 2?
?
Sr3 (PO4)2 is a crystalline substance used in medicine and industry. How many phosphorus atoms are represented in the formula for
Sr3 (PO4 ) 2?
?
a)
2
b)
3
c)
4
d)
8
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