Chemical Reactions

Which best describes a chemical reaction?

• the rearrangement of atoms by breaking and reforming chemical bonds

• a reaction that absorbs heat from the surroundings

• a reaction that releases heat to the surroundings

• the rearrangement of molecules based on temperature and pressure

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which is an example of a chemical reaction?

• paper folded into tiny pieces

• paper burned and turned into smoke

• paper soaked in water

• paper shredded and turned into pulp

Tags

NGSS.MS-PS1-2

Pedro wants to create a chemical reaction between oil and water. He adds oil to a beaker of water and notices that the liquids do not mix. He then shakes the beaker and the drops of oil become suspended through the water for a few moments before returning to their separate layers.

Did Pedro succeed in creating a chemical change?

• Yes, because the oil was evenly suspended.

• Yes, because the solution was permanently changed.

• No, because the oil only briefly mixed with the water.

• No, because no new substances were formed.

Tags

NGSS.MS-PS1-2

The Statue of Liberty is made out of copper and was once shiny and copper-colored. Over the years, the copper has gone through a process called oxidation, where it has changed into a new material.

What has occurred?

• an endothermic reaction

• an energy formation

• a chemical reaction

• a precipitate formation

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which of these most likely represents a chemical change?

• water boiling

• sugars digested by saliva

• mud drying to dirt

• ice cream melting

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

The expression CaCO₃ → CaO + CO₂ is an example of a

• reactant.

• product.

• chemical equation.

• chemical progression.

Tags

NGSS.MS-PS1-2

What is the number “4” in SiCl₄?

• a subscript

• a coefficient

• a product

• a reactant

Tags

NGSS.MS-PS1-1

Which symbol in a chemical equation separates the reactants from the products?

• =

• →

• >

• +

30 grams of lead oxide and 15 grams of ammonia react completely to produce solid lead, nitrogen gas, and liquid water. What will be approximate mass of all three products?

• 10 g

• 15 g

• 45 g

• 450 g

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which best represents the law of conservation of mass?

• mass of reactants > mass of products

• mass of reactants < mass of products

• mass of reactants = mass of products

• mass of reactants → mass of products

Tags

NGSS.MS-PS1-5