8 P 1 3, 8 P 1 4

When iron combines with oxygen in a moist environment, rust forms because of a 

• chemical reaction
• physical reaction
• change in density 
• change in temperature

Some power plants produce energy by burning coal.  In these power plants, the heat from burning coal is used to boil water.  Which statement best describes the changes that occur when burning coal and boiling water?

• Burning coal and boiling water are both physical changes
• Burning coal and boiling water are both chemical changes 
• Burning coal is a chemical change and boiling of water is a physical change
• Burning coal is physical change and boiling water is a chemical change

Which characteristic property of iron is mostly closely related to the formation of rust?

• chemical reactivity
• melting point
• specific heat 
• solubility

Which is indicated if a gas forms when two or more substances are mixed?

• physical change
• chemical change 
• physical property
• chemical property

Which statement best describes the formation of rust?

• Rust results from a physical mixing of iron with water
• rust forms from a chemical breakdown of old metal
• rust results from a chemical reaction between iron and water
• rust forms from a physical change when wind blows against metal

A beaker contains a sample of water with a mass of 325 grams. The water in the beaker is boiled and weighed again after it cools. The new mass of the water is 305 grams. In this example of the conservation of matter in physical changes

• the mass is less after it cools because water has less mass as a gas
• the mass of the water was 305 grams and the mass of the water vapor was 20 grams
• the procecss pf boiling destroyed 20 grams of the water and left 305 grams of water
• the heat energy created by boiling water makes up the rest of the maps

Which is a physical change?

• a piece of wood burning
• a copper roof changing color
• rust forming on an iron fence
• a sheet of paper shredding

which is represented when liquid water becomes a gas at 100 degrees celsius?

• density of water
• solubility of water
• boiling of water 
• chemical reactivity of water 

Max combines baking soda and vinegar in a flask. Which is the most likely reason Max should place a balloon over the mouth of the flask before he mixes the two substances?

• to prevent any gas formed as a product from escaping during the reaction
• to prevent any liquid used as a reactant from escaping during the reaction
• to prevent any powder used as a reactant from escaping during the reaction 
• to prevent any liquid formed as a product from escaping during the reaction

Matt placed a thermometer in a container of water and sealed the container.  The thermometer showed 22 degrees celsius.  When Matt returned afteran hour, he noticed the temperature had increased to 25 degrees celsius.  Which describes the change in water?

• The water increased its mass
• The water increased its density
• The water experienced a physical change
• The water experienced a chemical change