Sodium is a group 1 element with atomic number 1. It has 11 electrons. It is soft reactive metal. It has 1 valence electron.
Fluorine is a group 7 element, a hologen with 7 valence electron. It is a most reactive non metal.
When sodium react with fluorine, ionic bond is formed in the resulting compound sodium fluoride.
One sodium and fluorine each totaling 2 atoms are enough to make the bond.
As the bond is formed, both atoms have octet structure. That is they each have 8 electrons on their outermost shells.
The positive charge on sodium indicates that sodium had lost 1 electron to fluorine atom.
The negative charge on fluorine ion indicates that fluorine atom had gained 1 electron from sodium atom to form negative ion.
The name of the compound is sodium fluoride with formula NaF.
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+deltaS
-deltaH
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(2 Points)
A. mass x speed
B. 1/2 mass x velocity
C. mass x velocity
D. 1/2 mass x velocity squared
Answer:
D
Explanation:
(2) charge and orientation
(3) energy and mass
(4) energy and orientation
An effective collision between reactant particles requires the particles to have the proper energy and orientation. The particles must have the minimum energy to collide with each other and proper orientation to overlap.
Collision is a short term force acting between two object when they hit together. According to the kinetic molecular theory of matter, only effective collisions leads to the chemical bonding between atoms.
To make effective collisions, the atoms or constituent particles must acquire a minimum amount of energy to overcome the barrier potential of reaction.
Similarly, the particles must have proper orientation to have overlapping between their valence shell and form chemical bonds. Inappropriate orientation does not leads to the formation of bond between particles. Hence, option 4 is correct.
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B
It changes direction when it passes through an opening
С
It changes its speed and wavelength when it passes through an opening
D
It changes direction when it passes from one medium to another
E
It changes its speed and wavelength from one medium to another.
F
It changes direction when it bounces off of a solid surface.
If a sound wave refracts,It changes its speed and wavelength when it bounces off of a solid surface,It changes its speed and wavelength when it passes through an opening, and It changes direction when it passes from one medium to another. Therefore, option A, C and D are correct.
An important case in which sound waves change form or spread out is called refraction. This phenomenon affects the bending of a sound wave owing to changes in the wave's speed.
Refraction is the reason ocean waves near a shore parallel to the beach and why glass lenses can be used to focus light waves.
If the air above the earth is warmed than that at the surface, sound will be change shape back downward toward the surface by refraction. Soundpropagates in all directions from a point source.
Thus, option A, C and D are correct.
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Answer: To find Dave's speed, you can use the formula for speed, which is:
Speed = Distance / Time
In this case, Dave ran 2000 meters in 25 minutes. First, you'll need to convert the time to hours, as speed is typically measured in meters per second or meters per hour. There are 60 minutes in an hour, so:
25 minutes = 25 / 60 = 5/12 hours
Now, you can calculate Dave's speed:
Speed = 2000 meters / (5/12) hours
To divide by a fraction, you can multiply by its reciprocal (flip it):
Speed = 2000 meters / (5/12 hours) = 2000 meters * (12/5) hours
Now, calculate the speed:
Speed = 4800 meters per hour
So, Dave's speed is 4800 meters per hour.
Explanation: hope this helps :D