PHYSICAL OR CHEMICAL?
PHYSICAL AND CHEMICAL
LAW OF CONSERVATION OF MASS
TEMPERATURE & CHEMICAL CHANGES
MYSTERY QUESTIONS!
100
There are signs that can show a chemical reaction is taking place. Which of the following shows a sign that a chemical reaction is taking place? a) lava hardens and forms igneous rock b) a branch is pulled from a tree by an elephant c) smoke is blown from a chimney and dispersed d) a cup of milk is left on the table for two days and gets stinky
d) a cup of milk is left on the table for two days and gets stinky
100
Chemical changes result in new substances, but physical changes do not. Which process is an example of a physical change? a) pizza being cooked in an oven b) the chain of a bicycle rusting c) gold being melted and formed into bars d) a cheese sandwich you left under your bed getting moldy
c) gold being melted and formed into bars
100
You have learned the law of conservation of mass. Which of the following observes this law? a) most chemical changes b) all physical changes and chemical changes c) the majority of changes of state d) some physical changes
b) all physical changes and chemical changes
100
RonTravis is making waffles. He knows the cooking process of is an example of a chemical change because, for example, when he adds the baking powder, a gas forms. He gets distracted and burns a couple of them. What causes RonTravis's burnt waffles? a) the recipe that he uses b) the amount of batter he puts on the waffle iron c) the lower temperature he uses to make the waffles d) time and the higher temperature he uses to make them
d) time and the higher temperature he uses to make them
100
Zarhia squeezes a lemon and adds water to it. She then adds 22 grams of sugar to the mixture. She ends up with 142 grams of lemonade. What was the mass of the sugar and water solution that she started with? a) 20 grams b) 86 grams c) 100 grams d) 120 grams
d) 120 grams
200
The Hulk rips his shirt – again. This is an example of what kind of change? a) a change in energy b) a chemical change c) a change in mass d) a physical change
d) a physical change
200
There are several differences between physical and chemical changes. Which process is an example of a chemical change? a) laundry drying on a line b) ice melting in Antarctica as a result of climate change c) steam rising from a cup of hot chocolate d) grape juice turning to wine through alcoholic fermentation
d) grape juice turning to wine through alcoholic fermentation
200
When Ms. Clifford grills (and burns a bit) three fish, the mass of the fish is less than before they were grilled. Which statement best explains this result? a) The burnt fish has less volume than the raw fish. b) Some of the matter is destroyed through grilling. c) The mass of the fish cannot be accurately determined. d) Some of the products of the reaction are given off as a gas.
d) Some of the products of the reaction are given off as a gas.
200
Aaliyah had a yellow glowstick that she got at a friend's birthday party. When she got home, Aaliyah accidentally knocked the glowstick into the sink where the dishes were soaking in hot water. What happened? a) nothing - the chemicals in the glowstick were in plastic b) the higher temperature made the glowstick brighter c) the glowstick dimmed because of the change in temperature d) nothing - temperature has no affect on chemical reactions
b) the higher temperature made the glowstick brighter
200
A molecule of chlorine (Cl2) reacts with magnesium bromide (MgBr) causing a rearrangement of atoms. What is the result of this process? a) the bonds of molecules/compounds cannot be broken so it becomes a mixture b) smaller, simpler atoms are formed c) all bonds are broken between atoms d) different molecules/compounds are formed with different properties
d) different molecules/compounds are formed with different properties
300
If the picture on the left represents a solid and the picture on the right represents a gas, what has happened? a) a physical change (sublimation) b) a change in reactions c) a chemical change d) a change in mass
a) a physical change (sublimation)
300
Which process is an example of a chemical change? a) water condensing on leaves b) a glass bottle breaking when left in the freezer c) a lock rusting on a gate outside d) copper and zinc being mixed to create brass
c) a lock rusting on a gate outside
300
When Michelle, wanting to experiment at home, adds 20 grams of baking soda to 200 grams of white vinegar, the mixture begins to bubble. After 10 minutes, Michelle weighs the new mixture and finds that it is 210 grams. Why has the mass changed? a) some of the vinegar evaporated b) because the baking soda dissolved in the vinegar c) a gas was formed that left the mixture d) mixtures are always less massive than their parts
c) a gas was formed that left the mixture
300
Temperature can affect both the state of matter and the rate of chemical reactions. Which is an example of temperature affecting the rate of chemical reaction? a) hair drying more quickly when a blow-dryer is used b) dough rising more quickly when put in a warm oven c) coffee cooling more quickly when poured over ice d) water evaporating less quickly in lower temperatures
b) dough rising more quickly when put in a warm oven
300
Fe + O2 → Fe2O3 does not follow the law of conservation of mass because of which of the following? a) The mass of oxygen cannot be determined. b) There are two elements (Fe – iron and O – oxygen) on the left and only one compound (Fe2O3) on the right. c) There are three atoms on the left and five on the right side of the equation. d) Metals cannot react with gases.
c) There are three atoms on the left and five on the right side of the equation.
400
Which of the following shows indications of a chemical change? a) the color of Roberto's shirt changing when it dries b) the temperature of Sundrena's mug getting warmer when she drinks tea from it c) the smell of a lemon when it is squeezed d) the texture and color of iron when left outside in the rain
d) the texture and color of iron when left outside in the rain
400
Emanuel, in his science lab, mixed 15 grams of sodium bicarbonate into 25 milliliters of a citric acid solution in a beaker. The temperature of the mixture dropped and a gas was released. What happened in the beaker? a) evaporation b) a change of state from a liquid to a solid c) a physical change d) a chemical change
d) a chemical change
400
Eric mixes a solid (12 grams) and a liquid (30 grams) in a beaker (58 grams with stopper) and places the stopper on the beaker so that gases cannot escape. He sees many bubbles forming in the beaker, which he knows is a sign that a chemical reaction is taking place. The combined mass of the beaker, stopper, solid, and liquid is 100 grams. What should Eric expect the mass to be after the reaction and the formation of the gas? a) less due to the formation of the gas b) 100 grams c) more due to new substances being created d) 200 grams
b) 100 grams
400
Alisia mixed, in a beaker, two solid powders in her chemistry lab. The temperature of the substance changed from 26 degrees Celsius to 23 degrees Celsius. Which of the following best describes what happened in Alisia's beaker? a) a solution was formed b) a heterogeneous mixture was created c) a chemical reaction took place d) a physical change took place
c) a chemical reaction took place
400
A chemical reaction occurs between methane (CH4) and oxygen (O2). The arrangement of the atoms changes as a result of the reaction. What results from this reaction? a) New atoms are formed b) The mixture is separated into its component parts. c) Different compounds/molecules are formed with different properties. d) Bonds are not formed or broken in chemical reactions, thereby proving the law of conservation of mass.
c) Different compounds/molecules are formed with different properties.
500
Which type of change does the diagram show? a) a compound breaking down to form a new compound with another element b) two compounds breaking down c) two compounds breaking down to form two new compounds d) a physical change
a) a compound breaking down to form a new compound with another element
500
Which of the following is a physical change? a) bleach turning a shirt white b) milk curdling when mixed with lemon juice c) the color and texture of wood changing after being sanded d) the hardness of a banana changing after ripening
c) the color and texture of wood changing after being sanded
500
What is the law of conservation of mass? a) When elements and compounds react to form new products, mass is not lost or gained. b) The rule that we cannot waste elements that need our protection. c) The belief that mass never changes, no matter what planet you're on. d) The law that says that mass is better when it's conserved.
a) When elements and compounds react to form new products, mass is not lost or gained.
500
Javier put a bottle of juice in the freezer because he wanted it to cool quickly. He forgot that he had put the bottle in the freezer and the next day found a broken bottle in the freezer. What happened? a) a chemical reaction due to the cold temperature b) a physical change c) both a physical and chemical change in the juice d) neither a physical nor a chemical change
b) a physical change
500
In high school science, Brandon is given a mixture of sugar, iron pellets, and dried beans. His teacher gives him a magnet, hot water, and a filter to separate the mixture. Which is true about what Brandon does to separate the three parts of the mixture? a) he uses only chemical changes b) he cannot separate the mixture with the tools he has c) he uses both physical and chemical changes d) he uses only physical changes
d) he uses only physical changes
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