Molecular formula of water molecule is H₂O.
An initiator is someone who starts something. Example: She initiated the fight.
The time taken by the swimmer was 1 hour.
Why?
Since the swimmer is maintaining an angle of 150° while he was swimming, there were two components of the speed (horizontal and vertical). If we want to calculate the time taken by him to cross the river, we need to calculate the vertical speed and consider that the flow's speed is compensated by his horizontal speed.
We can calculate both components of the speed using the following formula:

Now, calculating we have:

Therefore, we have that the horizontal speed is compesating the flow's speed while his vertical speed is used to cross the river which is 1 Km wide.
Hence, we have that the tame taken is:

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The Earth's axis' orientation in space gradually shifts due to the precession.
Precession is the name given to this motion, which is characterized by a cyclic wobble in the direction of the Earth's axis of rotation over a period of 25,772 years. The third motion of the Earth to be discovered, following the much more evident daily rotation and yearly revolution, is precession. The axial tilt of the Earth gradually changes over time as a result of precession. The points on the Earth's orbit where the equinoxes and solstices fall will shift over time. As a result, 13,000 years from now, the location of the summer solstice will change to that of the winter solstice. The Earth's axis changes its direction due to precession. In relation to the stars, the celestial poles steadily shift.
Learn more about precession here-
brainly.com/question/17180029
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