Science exam

How can you be sure a chemical reaction is happening?
A mixture is made
A new substance is formed
Water turns to steam
A solid dissolves
Acids conduct electric current by forming
Hydrogen gas
Hydronium ions
Hydroxide ions
Hydrochloric acids
Which of the following occurs when water freezes?
A diatomic bond
A chemical bond
A chemical reaction
A physical change
Which of the following is the chemical formula for a dinitrogen trioxide molecule?
2NзO₂
NOз
N₂Oз
3N₂O
Nitrogen dioxide is a covalent compound. How many nitrogen atom(s) are in a nitrogen dioxide molecule?
0
2
3
1
Which of the following uses coefficients correctly to balance the equation N₂+3H₂ -> 2NHз
N₂+3H₂ -> 2NHз
N₂+H₂ -> NHз
2N₂+2H₂ -> 4NHз
3N₂+4N₂ -> 6NHз
Which of the following describes what occurs when chlorophyll breaks down into new substances?
Physical reaction
Balanced reaction
Chemical reaction
Unbalanced reaction
How many atoms are represented in the formula CaCOз
Six
Four
Five
Three
How many oxygen atoms are present in the reactant side of the chemical equation 4Fe+3O₂ ->2Fe₂Oз
2
4
6
3
Which of the following examples shows where a coefficient is used correctly to balance the equation?
2Na+Cl₂ -> 2NaCl₂
Na+Cl₂ -> 2NaCl
Na+2Cl₂ -> 2NaCl
2Na+Cl₂ -> 2NaCl
If a chemical symbol in a chemical formula has no subscript, it means
The chemical is listed last in the formula
The chemical symbol is written without any numbers
The element has no change
Only one atom of the element is in the molecule
For a chemical bond to break
Individual atoms must be present
Solids must be dissolved
Covalent compounds must be mixed
Energy is required
The symbol for iron is Fe. The chemical symbol for oxygen is O. The formula for iron oxide, a type of rust, is Fe₂Oз. How many iron atoms are in one molecule of iron oxide?
1
2
3
4
Which of the following states the law of conservation of mass?
Atoms are rearranged in a reaction and join new molecules
Energy is niether created nor destroyed in a chemical compound
Compounds form a new compound with different properties
Mass cannot be created or destroyed in a chemical reaction
What is O₂ an example of?
Chemical bond
Chlorophyll
Diatomic molecule
Sulfuric acid
Which of the following equations shows an exothermic reaction?
CaCOз + energy -> CaO + CO₂
2Na + Cl₂ -> 2NaCl + energy
2H₂O + energy -> 2H₂ + O₂
6CO₂ + 6H₂O + energy -> C₆H₁₂O₆ + 6O₂
Which of the following usually increases the rate of a reaction?
Grinding a solid reactant into a powder
Decreasing the concentration of the reactants
Lowering the temperature of the reactants
Raising the temperature of the products
If you know that Zn stands for Zinc and 2HCl stands for hydrochloric acid, you can tell what this equation represents: 2HCl + Zn -> H₂ + ZnCl₂
An acid reacting with a metal to produce hydrogen gas
A salt being formed from ions
An indicator changing color to show that something is an acid
A weak base reacting with a strong acid
Which of the following phrases describes a catalyst?
Changes permanently when used in a reaction
Increases the energy given off by a reaction
Slows the rate of reaction
Lowers the activation energy of a reaction
Which of the following is the product in the chemical formula N+O₂->NO₂
N+O₂
NO₂
O₂
N
How many atoms can be a carbon atom make bonds with?
Four
Three
Two
One
What compound used in cleaners feels slippery?
Sugar
Acid
Salt
Base
What products would form when hydrochloric acid, HCl, and sodium hydroxide, NaOH, react
In what ways do changed in pH affect the environment and living things? Give two ways.
Would you expect the pH sample of acid rain to be 4 or 9? Why?
Classify each of the following compounds as acidic or basic: soap, vinegar, vitamin C, baking soda, ammonia, lemonade, magnesium hydroxide
What is the difference between a reactant and a catalyst?
Compare the law of conservation of mass with the law of conservation of energy in a chemical equation
Your dog ran away from home at 1:00 this afternoon. It is now 1:30. You know that he walks with an average speed of 1m/s. Which of the following pieces of information is most important for finding your dog?
If the dog was chasing a squirrel
Which direction the dog is going
Whether the dog is alone
Whether the dog eaten recently
Dividing the total distance traveled by the total time time is how to calculate
Average velocity
Average acceleration
Average motion
Average speed
Which of the following are two factors that determine speed?
Distance and time
Velocity and time
Acceleration and time
Motion and time
The graph shows distance traveled during a bicycle race. Because the upward slope on the graph is straight and objects do not normally travel at a constant rate, what does it MOST likely represent?
Average acceleration
Actual speed
Average speed
Actual acceleration
A driver of an SUV drives past a jogger on a subdivision walking path. Relative to the jogger, the SUV is traveling 15m/s. What is the reference point in this situation?
The road on which the SUV is traveling
The SUV
The path on which the jogger is traveling
The jogger
What would you call a building if you compared it with a moving student?
A beacon
A ruler
A reference point
A compass
What is an object that appears to stay in place that helps you detect motion in another object?
A black hole
A lubricant
A newton
A reference point
If you jog for 1 h and travel 10 km, 10km/h describes your
Momentum
Average speed
Displacement
Acceleration
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