WorksheetsNC 8th Science 8.P.1 Review
Total questions: 44
Worksheet time: 22mins
Which is the best example of a pure substance?
peanuts
milk
gold
air
This chart represents several compounds and their chemical formulas. Which explains why the same elements can create many different compounds?
Elements combine in the same way to produce a variety of substances.
Elements have the ability to change electron size in order to combine with many different elements.
Elements combine in a multitude of ways to produce compounds that account for all living and nonliving substances.
Why does hydrogen (H) have a different subscript in each substance?
The subscript indicates the number of hydrogen atoms in each substance.
The subscript indicates the number of mixtures that the hydrogen is forming.
The subscript indicates the number of compounds that the hydrogen is forming.
The subscript indicates whether the hydrogen is forming a compound or a mixture.
The table shows the chemical formulas for several common household substances. Which two elements make up household ammonia?
neon and helium
neon and hydrogen
nitrogen and helium
nitrogen and hydrogen
The table below shows common compounds and their chemical formulas. Which can best be concluded from this information?
Some compounds contain only one element.
All compounds contain the same number of elements.
Elements combine in many ways to form different compounds.
Elements combine in the same way to form different compounds.
Sodium (Na) and chlorine (Cl) combine to form table salt (NaCl). How many sodium (Na) atoms are there for every chlorine atom (Cl)?
two sodium (Na) atoms for every one chlorine (Cl) atom
one sodium (Na) atom for every one chlorine (Cl) atom
one sodium (Na) atom for every two chlorine (Cl) atoms
In which state of matter will the atoms of an element be tightly packed together?
gas
liquid
solid
How are atoms combined in a mixture?
chemically combined and cannot be separated
physically combined and can be separated
chemically combined and can be separated
How can mixtures best be described?
made of one element
made of different elements that are all chemically bonded together
made of different elements that are not all chemically bonded together
Hydrogen peroxide (H₂O₂) and water (H₂O) both contain hydrogen (H) and oxygen (O). Why are they different compounds?
Hydrogen peroxide contains one more oxygen than water.
Hydrogen peroxide contains two more oxygens than water.
Hydrogen peroxide contains one less oxygen than water.
The table shows properties of several elements. Which element would Element X most likely be grouped with on the periodic table?
calcium
chlorine
copper
potassium
Which pair of elements has the most similar properties?
Li and B
I and Ca
K and He
N and P
Which element will most likely gain electrons?
Cl
Na
Ne
Where on the periodic table are you most likely to find elements that do not react with other elements?
group 1
group 17
group 18
If an element has no electrons to share and is stable, what family is it found in?
alkali metals
noble gases
halogens
What is the significance of metalloids in the periodic table?
They separate liquids from solids.
They separate metals from nonmetals.
They combine elements and compounds.
Why are certain elements placed into the same column on the periodic table?
They have the same number of protons in their nuclei.
They have the same number of electrons in their nuclei.
They have the same number of electrons in their outer energy level.
Which elements are most likely to react in the same manner in a chemical reaction?
elements in the same group
elements in the same period
elements with similar atomic masses
What best describes the reactivity of alkali metals?
Reactivity increases left to right across a period.
Reactivity decreases left to right across a period.
Reactivity increases down a group.
What happens to water molecules during the boiling process?
They move faster and move farther apart as they absorb heat.
They move faster and remain close together as they absorb heat.
They move more slowly but move farther apart as they lose heat.
They move faster and move farther apart as they lose heat.
An ice cube is put into a heated pan. What will most likely happen to the molecules in the ice as the ice is heated?
The molecules will begin to move slower.
The molecules will begin to move faster.
The molecules will begin to increase in density.
The molecules will begin to condense in the air.
Which shows one example of a physical change and one example of a chemical change?
boiling water and melting wax
rusting iron and baking a cake
dissolving powder and shredding paper
freezing water and burning coal
Sugar is dissolved in a glass of hot water until no more sugar will dissolve. As the glass of hot water cools, a white crystalline solid is observed on the bottom of the glass. Which best describes the identity of the white crystalline solid?
The white crystalline solid is sugar.
The white crystalline solid is an impurity in the water.
The white crystalline solid is produced from the mixture of sugar and water.
Baking soda and vinegar was mixed and a match was struck. Which best explains why the lit match went out when placed in the mouth of the flask?
The baking soda and vinegar reacted to produce hydrogen gas. The hydrogen gas caused the lit match to go out.
The baking soda and vinegar reacted to produce oxygen gas. The oxygen gas caused the lit match to go out.
The baking soda and vinegar reacted to produce carbon dioxide gas. The carbon dioxide gas caused the lit match to go out.
What is the best way to measure the gas produced in a chemical reaction?
Perform the experiment in a beaker.
Perform the experiment in a room.
Perform the experiment in a closed system.
When a marshmallow is toasted over a fire, which is the best description for what happens to the outside of the marshmallow?
chemical change
physical change
enzyme creation
Two clear solutions are mixed together in a beaker. Which result would indicate a chemical reaction had occurred between these solutions?
increase of volume in the beaker
decrease of volume in the beaker
increase in temperature of the beaker
What is the best evidence for a chemical reaction?
color change
cutting a metal
change of state
Which chemical change occurs due to mixing baking soda and vinegar?
combustion
gas production
heat production
Batteries lose effectiveness over time because of chemical reactions that occur in the batteries. Where is the best place to store batteries to keep them for a longer period of time?
Store them in a car.
Store them in water.
Store them at room temperature.
Which best represents a balanced equation?
HgO → Hg + O2
2Fe + O2 → Fe2O3
2H2 + O2 → 2H2O
Which is best represented by the equation? 2Mg + O2 → 2MgO
Law of Conservation of Energy
Law of Conservation of Mass
Law of Superposition
How does a balanced chemical equation satisfy the Law of Conservation of Mass?
During a chemical reaction, the total amount of matter stays the same
During a chemical reaction, matter is destroyed
During a chemical reaction, one or more new substances are formed
During a chemical reaction, the total number of atoms increases
If a chemical reaction such as photosynthesis begins with 6 atoms of carbon (C), how many atoms of carbon (C) should be in the products?
12 atoms of carbon (C)
6 atoms of carbon (C)
3 atoms of carbon (C)
2 atoms of carbon (C)
Which best explains why the total mass of the product(s) would be less than the total weight of the reactant(s) after a chemical reaction?
A physical change occurred.
Atoms involved in the reaction lost mass.
Precipitates were created in the new solution.
Gases were released to the atmosphere
Which best describes how to balance the chemical equation shown below to support the law of conservation of mass?
Add the coefficient 2 before the Mg on both sides of the equation.
Add the coefficient 2 before the O2 on the left side of the equation.
Add the coefficient 2 before the Mg on the left side of the equation.
Add the coefficient 2 before the MgO on the right side of the equation.
Which best explains why the equation is not balanced? The equation below shows a reaction between sodium (Na) and water (H2O).
There is too much sodium in the reactants.
There is not enough water in the reactants.
There is too much hydrogen gas in the products.
There is not enough sodium hydroxide in the products.
In the equation below, suppose 11 grams of zinc react with 12 grams of hydrogen chloride to form 16 grams of zinc chloride and an unknown amount of hydrogen gas. Zn + 2HCl → ZnCl2 + H2 Based on the Law of Conservation of Mass, how many grams of hydrogen gas will form?
1 gram
7 grams
19 grams
Which best represents a balanced equation?
120 grams of carbon plus 20 grams of oxygen → 200 grams of carbon dioxide
120 grams of carbon plus 50 grams of oxygen → 200 grams of carbon dioxide
120 grams of carbon plus 80 grams of oxygen → 200 grams of carbon dioxide
The reaction below takes place in a closed system. CaCO3 → CaO + CO2 Which best describes this balanced equation?
More products and less reactants are produced.
More reactants and less products are produced.
Reactants and products are equal in the chemical reaction.
The conversion of 7.0 grams of carbon monoxide and 7.5 grams of nitrogen monoxide using 3.0 grams of platinum catalyst is shown. Which best represents the total mass of carbon dioxide and nitrogen gases produced in this process?
3.5 grams
10.5 grams
14.5 grams
What is the total number of oxygen atoms on the reactant side of the equation shown?
2
3
5
7
This chemical reaction occurs. How many atoms of hydrogen are involved in the reaction?
1
2
4
8
A chemical reaction occurs. Based on the law of conservation of mass, how much hydrogen gas is produced compared to the amount of oxygen produced?
half as much
twice as much
the same amount
four times as much
