8th Grade Winter Science Final Review
In an experiment, two flasks of unknown, clear liquids are combined in a beaker and the following observations are obtained: Solution remains clear, Amount of solution increased, temperature changed from 10 degrees C to 20 degrees C, and some of the liquid remained in the flask. How many of the listed observations indicate that a new substance was formed?
1.
A chemical formula is provided.(NH4)2CO3. How many atoms of Hydrogen (H) are found in this substance?
8.
Write about a situation where it might be more useful to describe motion using velocity instead of speed.
A car crashes into a telephone pole on the right side of the road and the police are trying to investigate what caused this to happen. Yes, speed would help see how hard hit the pole and how much force it takes to obliterate the pole. But, let's say there's a pothole in the middle of the road. That could help the police see where a tire could've hit in just the right spot to spin the car out of the control to the right of the road.
An element's reactivity and other chemical properties are determined by the number of-
Valance electrons.
A rate of motion in a specific direction is
Velocity.
Any change in an object speed or direction.
Velocity.
The object's __________ is 2 m/s north.
Velocity.
If a boy is pulling 40 N to the left and another is pulling 50 N to the right, what is the net force on the rope?
10 N right.
What is the mass of an atom with seven protons, seven neutrons, and eight electrons?
14.
If the force of a ball is 20 N and the force of friction is pushing 3.7 N back, what is the net force of the ball?
16.3.
At which time did the temperature first reach 65 degrees C?
40 seconds.
If a girl is pushing 40 N to the right and a girl is pushing 35 N to the left, what is the net force on the box?
5 N right.
What is the name for the type of subatomic particle that is electrically neutral and found in the nucleus of an atom?
A neutron.
Engineers also have to think about safety in the cars they design. Describe how a vehicle restraint such as a seatbelt shows Newton's first law of motion when it helps keep you safe in a car crash.
A seatbelt shows Newton's first law of motion because the car stays in motion until it's hit by an unbalanced force. The car might stop but you'll still be in motion until an unbalanced force hits you like a window. So a seat belt keeps your strapped so you don't fly when the car gets hit.
Water is an example of a compound. Which of the following is the Best description of all compounds.
A substance that is made up of more than one kind of atom.
A change in the rate of motion or direction is
Acceleration.
The units for _____________ are meters per second or meters per second squared (m/s2).
Acceleration.
For every _________ there is an equal and opposite reaction.
Action.
In which of the following examples has a chemical reaction occurred?
After putting liquid batter into a hot pan, the batter solidifies and begins to turn brown.
Which of the following correctly lists the pair of subatomic particles that balance the charge of the atom?
Protons and electrons.
An equation can be balanced by adding a number two in which location?
B.
Which of the following examples shows that a chemical reaction has occurred?
Bleach gets rid of a ketchup stain on a white shirt.
Which equation below is correctly balanced?
C12H22O11+12O->12CO2+11H20.
Which of the following properties of carbon distinguishes it from all other elements?
Carbon has six protons in its nucleus.
Molybdenum has an atomic number of 42. That means that molybdenum-
Contains 42 protons and in its nucleus.
An object's velocity includes information about the _______________ of motion, but speed does not.
Direction.
This is included when describing velocity, but not in speed.
Direction.
Which subatomic particle(s) would be found orbiting around the nucleus?
Electrons only.
Explain to a classmate how they can use units to tell the difference between speed, velocity, and acceleration?
For speed they use distance divided by time or specifically meters per second. Velocity can use this but velocity includes direction which speed doesn't. Acceleration just shows the change and also meters per second squared unlike velocity and speed.
A push or pull that changes an objects motion.
Force.
You need more _________ to accelerate when you have a larger mass.
Force.
What is the correct way to write the formula for a water compound?
H2O2.
Newton's first law deals with ___________, which means that objects resist changes in their motion.
Inertia.
Which pair of elements would have the same number of valance electrons between Lithium, Beryllium, Sodium, and Magnesium?
Lithium and sodium.
A rocket with less _________ will have a greater acceleration during launch.
Mass.
According to the law of conservation of mass-
Matter isn't created or destroyed in a chemical reaction.
When moving down a column in the Periodic Table, which of the following increases?
Metallic character of the element.
Which of the following is decreasing as you move from left to right across the right portion of the Periodic Table?
Metallic character.
What equation is correctly balanced?
N2+3H2->2NH3.
Which of the following chemical formulas is written correctly? NACL, CO2(2 is top right), 6C12H6O, or NO3?
NO3.
This is always equal and opposite to the action force.
Newton's third law; Law of Action-Reaction.
An objects tendency to stay at rest or resist a change in motion.
Newtons first law; Law of Inertia.
A chemical formula is shown. C6H5OH. The subscripts in a chemical formula represent the-
Number of atoms of the element in front of the subscript.
Which of the following properties uniquely identifies every element?
Numbers of protons.
Between 1. The crystals dissolve, 2. A precipitate is formed, 3. The bottom of the beaker feels warm to the touch, and 4. Bubbles begin forming in the water, all observations are evidence of a chemical change EXCEPT-
Observation 1
Which element would have similar properties to Sulfur? Nitrogen, Oxygen, Fluorine, or Phosphorus?
Oxygen.
Which particles would you find in the nucleus of an atom?
Protons and neutrons.
When vinegar and baking soda are combined, bubbles begin to form. Bubbles are evidence of a chemical reaction because they-
Show that a gas is forming.
Out of sodium, strontium, phosphorus, and aluminum it can be concluded that-
Sodium is the most reactive.
An objects rate of motion is
Speed.
When you calculate __________, you use distance and time.
Speed.
If an object increases in speed, it must be as a result of-
Unbalanced forces.
Think about Newton's second law of motion. What would an engineer designing a rocket do to the rocket ship or its engine if he or she wanted to produce more acceleration?
The engineer would make the rocket ship have less mass. Therefore, it would be easier to launch into the air. For the engine, they'd make it bigger so it can produce more force against the gravity.
For an object to remain at rest, which of the following must be true?
The forces on it are balanced.
In which location on the Periodic Table are the non-metals found?
The top right corner(Location 3).
If a girl is pushing 35 N to the right and another girl is pushing 30 N to the left the box will accelerate which direction?
To the right.