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?

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

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?

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

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.

Classify each of the following compounds as acidic or basic: soap, vinegar, vitamin C, baking soda, ammonia, lemonade, magnesium hydroxide

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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