Answer:
18.99u or 19u
Explanation:
Mass number=No of protons+No of neutrons


- Fluorine has atomic number=9
- The Electronic configuration is given by

Answer:
Oscillation whose amplitude reduce with time are called damped oscillation. This happen because of the friction. In oscillation if its amplitude doesn't change with time then they are called Undamped oscillation
Magnetic stripes on the sea floor
Explanation:
The observation of magnetic stripes patterns at the region of the Mid-Atlantic Ridge galvanized the evidence that sea floor spreading has been on for several millions of years.
- Geomagnetic field of the earth is similar to that of bar magnet having the north and south pole.
- It originates from the movement of iron-nickel within the outer core.
- This geomagnetic field causes the magnetization of magnetic minerals in rock.
- When freshly formed magma is brought to the surface at the mid oceanic ridge area, the prevailing magnetic field causes the magnetic minerals in the magma to cool in such a way that they align their domains to that of the field.
- The magnetic field of the earth can reverse and take different geometry. Sometimes, its intensity is very strong and at other times it is weak.
- The magnetic minerals in melts bear these records.
- As new materials are brought up, they get magnetized.
Learn more:
Sea floor spreading brainly.com/question/9912731
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