Reviewing Density and Changes in Matter

Copper is added to a solution of nitric acid. The solution becomes hot and changes from colorless to blue. What is the best explanation for the change in temperature?

• The blue color absorbs less energy, which causes heat to be released.

• The increased volume of the solution causes heat to be released.

• The chemical reaction between the copper and nitric acid produces heat.

• The copper and nitric acid repel each other, which produces heat.

Jelena is studying the properties of water. She finds that a sample of 100 mL distilled water boils at 100°C and has a density of 1 g/mL. What will Jelena most likely find to be true about a sample of 200 mL distilled water?

• It will boil at 200°C and have a density of 2 g/mL

• It will boil at 100°C and have a density of 1 g/mL

• It will boil at 200°C and have a density of 1 g/mL

• It will boil at 100°C and have a density of 2 g/mL

Over time an iron nail reacts with water to produce iron oxide, or rust. Which of the following is a signal that rusting has taken place?

• The appearance of sparks.

• The release of an odor in the presence of bubbles.

• The release of heat and steam at the area where the mixture occurred.

• A color change on the nail from silver to reddish-brown.

Abner is researching the physical properties of pure copper. He makes this table using the data he finds. What could Abner conclude from his findings?

• Decreasing the mass of copper decreases the melting point of copper.

• Decreasing the mass of copper increases the density of copper. 

• Increasing the mass of copper always changes the color of copper.

• Increasing the mass of copper does not change the physical properties of copper. 

Of the following processes in nature, which one involves only a physical change?

• A bird digests a worm.

• Photosynthesis occurs in a leaf.

• An earthquake causes a rock slide.

• A chunk of iron ore rusts.

WHich of the following items would have the highest density?

• A 6 cm³ block of ice with a mass of 4 grams

• A 12 cm³ block of aluminum with a mass of 2 grams

• A 2 cm³ block of lead with a mass of 11 grams

• A 12 cm³ block of wood with a mass of 3 grams

A student is given a small sample of a pure solid substance. She is asked to identify the substance based on a particular property. Which property, if determined accurately, would best help her identify the substance?

• its mass

• its volume

• its temperature

• its density

When a small piece of white marble rock is carefully placed in a beaker of hydrochloric acid, bubbles form on the surface of the rock and rise to the top of the liquid.

Which conclusion best fits this observation?

• The rock dissolved in the acid by breaking into its smallest pieces

• The rock reacted with the acid and made a new gaseous substance

• The rock heated the acid until it began to boil

• The rock was changed by the acid into its gaseous form.

Which of the following is a chemical change?

• a rock eroding as the wind removes particles from it

• soil drying as water evaporates

• a solution of salt water being diluted as water is added to it

• silver tarnishing as the silver metal reacts with sulfur

Density is a measurable property of matter. How can the density of a substance be determined?

• Measure the length and weight of the substance, then multiply the length by the weight

• Measure the mass and volume of the substance, then divide the volume by the mass.

• Measure the length, width, and height of the substance, then multiply the values together

• Measure the mass and volume of the substance then divide the mass by the volume