You are hired as a scrap metal dealer. A customer wants to sell you a piece of precious scrap metal. You know it is one of these common metals. You slowly heat the metal and it melts at 962 °C. You also take the density of the metal and find it to be roughly 10.5 g/cm³. What is the MOST LIKELY identity of the metal?

• copper

• gold

• silver

• zinc

Tags

NGSS.MS-PS1-4

Which of the following explanations DOES NOT justify using filtration to separate sand from water?

• Sand is an insoluble solid that does not dissolve in water.

• The two parts of the mixture, sand and water, have different boiling points.

• Sand particles are large enough to be stopped by a piece of filter paper, separating the sand from the water.

• Although crystallization would separate the sand from the water, it would not provide a method to collect the water.

Salt plus water. Two compounds mixed together to form a solution. The water is the solvent; the salt the solute. Students have been tasked with separating the two compounds from solution. One group set up the distillation apparatus you see here. Explain the concept used to separate the salt and water.

• The separation of the water from the salt is based on the boiling point and condensing point of water.

• The separation is based on the temperature needed to change liquid water to a gas and then back again to a liquid: the boiling point.

• The separation of the two is based on different boiling points of the salt (higher) and the water (lower). When the solution is heated the water evaporates from the solution, leaving salt behind.

• The separation of the two is based on different boiling points of the salt (lower) and the water (higher). When the solution is heated the salt is transferred as water vapor collects in the condensing tube.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Which situation indicates a physical change?

• Solid copper melts to form liquid copper.

• A firecracker explodes on the fourth of July.

• Water reacts with the iron on your bicycle to form rust.

• Magnesium metal is mixed with hydrochloric acid and hydrogen gas is formed.

Mary Sue is making caramel ice cream. In the first part of the process, she combines a cup of sugar and a cup of water in a saucepan. She cooks the mixture over medium heat until the sugar melts and browns to a light amber color. Then she adds the same amount of water to the mixture along with a cup and a half of cream and milk.

Which part of the preparation indicated a chemical change?

• melting the sugar

• mixing the sugar with water

• adding cream and milk to the mixture

• sugar changes from white to a light amber color

Tags

NGSS.MS-PS1-2

During a science lab, some students added small pieces of magnesium ribbon to 10 mL of hydrochloric acid. They noticed that bubbles formed, the test tube got hot, and the magnesium disappeared. Which is a sign that a chemical reaction has taken place in this experiment?

• change in odor

• change in color

• release of heat energy

• disappearance of magnesium

Tags

NGSS.MS-PS1-2

Brad and Juan conducted several tests to determine the properties of silver metal. They noted that it was white, and conducted both electricity and heat. They computed the density to be 10.49 g/cm³. Silver did not react with water but in nitric acid, gas was released.

What evidence supports a chemical change in the silver?

• Silver is white in color.

• Silver conducts electricity and heat.

• Silver has a density of 10.49 g/cm³.

• Gas was released when silver reacted with nitric acid.

Tags

NGSS.MS-PS1-2

Which of the following indicates a chemical change?

• Silver conducts electricity.

• Silver reacts with nitric acid to produce a gas.

• The color of silver at room temperature is white.

• Silver conducted heat and as the temperature increased, became more malleable.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

This flask originally held some copper wire and a clear solution of nitric acid. The two substances reacted and produced a brown gas and a blue solution. This reaction cannot be reversed. Evidence of a chemical reaction is shown by

• ice forming.

• steam rising.

• the formation of a gas.

• a change in state from a solid to a liquid.

Tags

NGSS.MS-PS1-2

The task in science lab: discover which solid substance, without tasting, is sugar. Donna and Dave have five substances to test, and unfortunately, two are white! "Let's heat them!" suggested Donna. Did Donna have a reasonable solution to their problem?

• Yes, it would help narrow the search to salt or sugar.

• No, all four substances have pretty low melting points.

• No, it's impossible to reach these temperatures in a student lab.

• Yes, sugar's melting point is much lower than the other four solids.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4