Chemical Reactions

Which process is an example of a chemical change?

• Cooking a steak

• Chopping a tree

• Heating a cup of tea

• Drying clothes in the dryer

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Muqeet mixes iron filings, sand and salt. To separate the mixture, he uses a magnet, boiling water, and a filter. Which is true?

• Muqeet uses only physical changes to separate the mixture's components.

• Muqeet uses only chemical changes to separate the mixture's components

• Muqeet uses both physical and chemical changes to separate the mixture's components.

• Muqeet uses neither physical and chemical changes to separate the mixture's components.

A chemical reaction occurs. Which statement is true of the reactants and the products in the reaction?

• The atoms in the products were regrouped into different molecules to form the reactants.

• The atoms in the reactants were regrouped into different molecules to form the products.

• The atoms in the products were destroyed and new molecules appeared to form the reactants.

• The atoms in the reactants were destroyed and new molecules appeared to form the products.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

A student observed a precipitate form during a chemical reaction. Which of the following did the student most likely observe?

• Bubbles of gas floated to the top of a solution.

• The color of a liquid changed when a solid was added to it.

• Steam rose from a flask when a powder was added to a liquid.

• A solid sank to the bottom of a container when two liquids were mixed.

Tags

NGSS.MS-PS1-2

A powder is added to a liquid. Identify several properties of liquids, and explain how you could use these properties to obtain evidence to support the conclusion that a chemical reaction has occurred.

• The solution is clear and does not change color, showing a chemical reaction

• The solution becomes coffee, a chemical change

• The powder is not soluble and results in precipitate, a chemical change

• The solution smells and explodes, showing a chemical change

Tags

NGSS.MS-PS1-2

Defan made pancakes from batter, freshly squeezed orange juice, fried eggs, and a strawberry fruit salad. Identify the chemical changes that occur to the food items during breakfast preparation.

• Squeezing oranges and fried eggs are chemical changes

• Cooked pancakes and fried eggs are chemical changes

• Chopped fruit salad and cooked pancakes are chemical changes

• Fried eggs and sublimated dry ice are chemical change

Tags

NGSS.MS-PS1-2