7th Grade Science Topic Assessment Chemical Reactions

Early in the day, Josiah learned about the kinds of changes in matter that can take place.

Later that day, he made toast and buttered it, but then he left the butter out on the warm stove. What kind of change would most likely take place with the butter?

• chemical

• physical

• liquid

• solid

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

After having studied chemical reactions in school, Bryce knew that when oxygen and hydrogen gases combine in the correct amounts, the combination yields a new substance, water. Choose the words to finish the sentence.

The hydrogen and oxygen are ________, while the water is the_______

• wet, dry

• reactants, product

• product, reactants

• hot, cold

Tags

NGSS.MS-PS1-2

Gregory saw a rusty old car in an abandoned lot. Because he had recently read about chemical reactions, he began to wonder how the rust formed. What happened to cause the rust on the steel car?

• A physical change took place in the steel of the car to form rust.

• Oxygen in the air reacted with the paint on the car and formed rust.

• Oxygen in the air chemically combined with the iron in the steel to form rust.

• A decomposition chemical reaction took place when the iron in the steel mixed with oxygen to form rust.

Tags

NGSS.MS-PS1-2

After learning about the law of conservation of mass, Natalie began to wonder about how to best test this law. She wanted to show that the total amount of matter did not change, but a process produced the same amount of different kinds of matter. What is the best way to study this law?

• in a homogeneous mixture

• in a heterogeneous mixture

• in an open system

• in a closed system

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Carmelo was using a heavy duty glue one afternoon after learning about synthetic materials. Chemists create different kinds of new products based on their knowledge of the properties of substances and how they react with each other. Sometimes, chemists create a product different than what they intended to create, like the type of glue Carmelo used. What kind of product was this type of glue?

• accidental

• developed

• known

• planned

Tags

NGSS.MS-PS1-2

Londynn drinks water from plastic bottles. She knows the bottles are formed from synthetic polymers that are created in a chemical reaction. She also knows that synthetic materials can cause problems. Which statement explains one kind of problem that can develop from using synthetic materials such as plastic?

• Plastics have changed the way people use materials.

• Plastics have made the lives of people easier.

• Plastics have contributed to more pollution.

• Plastics have made more work for people.

Tags

NGSS.MS-PS1-3

Robert is researching alternative fuels and learns about different types of alcohol. They can be synthesized from wood and grasses or produced from crops that are already grown in many parts of the world. When mixed with gasoline, alcohol raises the octane, which makes the gasoline burn more efficiently. It also reduces the amount of pollutants released. Robert makes notes about a number of characteristics of alcohol fuels, as listed below. Which are BENEFITS?

• reduce air pollution, renewable

• more expensive than gasoline, contain less energy per liter

• require farmland, renewable, and raise octane

Tags

NGSS.HS-ESS3-4

NGSS.HS-ETS1-3

Chlorine bleach and ammonia are two common ingredients in home cleaning products. However, these products should never be mixed together while cleaning, because they can produce dangerous chemicals as a result of their reactions together. One of those reactions involves ammonia and bleach forming the dangerous product chloramine and the harmless product sodium hydroxide.

In these models, chlorine atoms are medium gray, nitrogen atoms are dark gray, sodium atoms have horizontal bands, oxygen atoms have vertical bands, and hydrogen atoms are light gray.

In this reaction, chloramine is a gas at room temperature. To determine if it follows the law of conservation of mass, the reaction should be carried out in a ____________ system.

The chloramine and sodium hydroxide should be weighed and compared to the weight of the ____________

• Closed, Reactants

• Opened, Products

• Dark, Systems

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Anthony decides to roast a marshmallow. Before roasting the marshmallow, Anthony observes that it smells like sugar. After holding the marshmallow over the campfire for 30 seconds, Anthony observes that the marshmallow smells like nuts.

Which statements explain the marshmallow’s change in smell? Choose the two that best apply.

• The heat energy of the fire burned the sugar in the marshmallow, producing a new, and different compound.

• A camper nearby opened a can of nuts. This caused the change in smell.

• The change in the marshmallow's odor is evidence that a chemical reaction occurred.

• The change in the marshmallow's odor is evidence of a physical change.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

When methane gas (CH4) is burned in the presence of oxygen (O2), the product is carbon dioxide (CO2) and water (H2O). The following diagram models this chemical reaction. The black circles represent carbon atoms. The white circles represent hydrogen atoms. The gray circles represent oxygen atoms.

Is mass conserved in the reaction between methane gas and oxygen?

• Yes, because the total number of atoms stays the same during the reaction.

• Yes, because the number of products matches the number of reactants.

• No, because the total number of atoms increases during the reaction.

• No, because the total number of atoms decreases during the reaction.

Tags

NGSS.MS-PS1-5