Explanation:
Geocentric model said that the Earth is at the center of the universe and everything revolves around it. It was considered to be stationary. Galileo proved this model incorrect with the help of his astronomical observations. Some of the key observation that he used to support the heliocentric model were:
1. He proposed the theory that the tides on the Earth occur because of its motion.
2. He observed the phases of the Venus which meant that the Venus revolved around the Sun and not the Earth.
3. He observed other planets and thus noted that they also move around the Sun and not Earth.
4. He discovered the Moons of other planets.
Answer:
The answer is (a.) An upward force balances the downward force gravity on the skydiver
The skydiver is falling at a constant velocity because the upward force is balancing the downward force of gravity. According to Newton, the opposite force balance each other. This is stated in Newton's second law of motion.
Answer:
Explanation:
Polyatomic ions are ions that contain more than one atom in each one of the ions.
Ionic compounds are made of cations (positive ions) and anions (negative ion). By convention, the cation is written before the anion.
List the ions in each compound:
<h3>CaCO₃</h3>
Cation: 
,
Anion: 
.
is a monatomic ion for it contains only one atom in each ion.
is a polyatomic ion for it contains four atoms (one C atom and three O atoms) in each ion.
<h3>NaF</h3>
Cation: 
,
Anion: 
.
Both and are monatomic for they contain only one atom in each ion.
<h3>FeO</h3>
Cation: 
,
Anion: 
.
Both and 
are monatomic for they contain only one atom in each ion.
<h3>CaCl₂</h3>
Cation: ,
Anion: 
.
Both and 
are monatomic for they contain only one atom in each ion.
<h3>NaOH</h3>
Cation: ,
Anion: 
.
is a monatomic ion for it contains only one atom in each ion.
is a polyatomic ion for it contains two atoms (one O atom and one H atom) in each ion.
Answer:
wavelength = v/f or wavelength equals to velocity over frequency
frequency= v/w or velocity over wavelength
frequency= 1/p or one over period or time
When there was know life on the earth
