Which gas is most abundant in the Earth's atmosphere?
Nitrogen.
Why do people not fall off the Earth at the South Pole?
Gravity pulls them toward the Earth's center, keeping them grounded.
How is weight defined?
Weight is the force of gravity acting on an object, measured in newtons.
A substance made up of only one type of atom is called a?
Element.
What are atoms?
Atoms are tiny particles that make up all matter, and cannot be divided any further.
What is the unit used to measure force?
Newton.
If there are 94 different kinds of naturally occurring atom, how many different naturally occurring elements are there?
There are 94 different naturally occurring elements.
What does the formula H₂O tell you about the numbers of each kind of atom that are combined together?
The formula tells you that there are two hydrogen atoms and one oxygen atom.
Does the Moon have gravity?
Yes, the Moon has gravity, though it is weaker than Earth's gravity.
If a rock weighs 8000 N, what is the contact force from the ground?
The contact force is also 8000 N.
What is the name of the force that pulls objects towards the Earth?
Gravity.
Find the symbols for the elements aluminium, boron, fluorine, and potassium.
Al, B, F, and K.
What are the names of the elements with the symbols Mg, Be, Li, and N?
Magnesium, Beryllium, Lithium, and Nitrogen.
On Earth, what is the value of gravitational strength?
It is approximately 10 N/kg.
Which two elements are combined in water?
Hydrogen and Oxygen.
The chemical formula for Water is?
H2O.
An elephant weighs 40,000 N and stands on four feet. What is the contact force on each foot?
The contact force on each foot is 10,000 N.
Which three elements are combined in calcium nitrate?
Calcium, Nitrogen, and Oxygen.
How does the mass of an object change when you move from Earth to the Moon?
The mass remains the same, but the weight decreases due to the lower gravity on the Moon.
Which of the elements in the first 20 elements of the Periodic Table has atoms with the greatest mass?
Calcium.
Why do car wheels begin to sink into soft mud?
The contact force from the mud is less than the weight of the car's wheels.
On Mars, if a 25 kg object has a weight of 92.5 N, what is the local gravitational strength?
The local gravitational strength on Mars is 3.7 N/kg.
What is the contact force?
The contact force is the force exerted by a surface to support an object resting on it.
What is the chemical formula for Magnesium Sulfate?
MgSO4.
If a box weighs 10 N and is resting on a desk, what is the contact force from the desk?
The contact force is 10 N.
Which three elements are combined in lithium sulfate?
Lithium, Sulfur, and Oxygen.
Which two elements are combined in magnesium oxide?
Magnesium and Oxygen.
How does the strength of gravity change as you move farther from Earth?
The gravitational force decreases as you move farther away from Earth.
Which two elements are combined in hydrogen sulfide?
Hydrogen and Sulfur.
Which of the following is not a planet in our Solar System?
Sun.
How many different elements are combined in sulfur dioxide?
Two elements, sulfur and oxygen.
What happens to the gravitational force on you as you travel in a spacecraft away from Earth?
The gravitational force acting on you will decrease.
Suggest the names of the compounds with these formulae: MgO, NaCl, CaCl₂.
Magnesium Oxide, Sodium Chloride, and Calcium Chloride.
What is the chemical symbol for Sodium?
Na.
Give the symbols (not names) of two elements in the same group as helium.
Ne and Ar.
What happens if the weight of an object exceeds the contact force?
The object may sink into the surface, or the surface may break.
Which two elements are combined in sodium chloride?
Sodium and Chlorine.
What is the force of gravity acting on an object called?
It is called weight.
What happens when the contact force from the mud increases with depth?
The wheels are supported more, preventing further sinking.
How many atoms of oxygen are combined with each atom of sulfur in sulfur dioxide?
Two oxygen atoms.
What is the mass of an object if its weight is 450 N on Earth?
The mass of the object is 45 kg.
How does the Earth's gravity affect objects with smaller masses?
The Earth's gravity pulls them toward its center, but the force is weaker compared to larger masses.
What is the difference between mass and weight?
Mass is the amount of matter in an object, measured in kilograms, while weight is the force exerted by gravity on that object, measured in newtons.
Which three elements are combined in magnesium carbonate?
Magnesium, Carbon, and Oxygen.
Give the names (not symbols) of two elements in the same period as magnesium.
Sodium and Aluminium.
Which element has atoms with the smallest mass?
Hydrogen.
What pulls an object to the ground when it is dropped?
Gravity from the Earth pulls it down.
A student wrote this name for a compound made of calcium and sulfur: sulfur calcium. What is wrong with this name? Write the correct name for the compound.
The correct name is Calcium Sulfide.
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