<h2>1. Right answer: Observational
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Kepler formulated the three laws of planetary motion <u>from observations made by</u> the Danish astronomer <u>Tycho Brahe of the orbit of Mars.
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These laws were enunciated to mathematically describe the movement of the planets in their orbits around the Sun. However, the scientific resources existing in his time did not allow him to prove these laws. It was Newton who did it after having developed the Differential and Integral Calculus and formulating the Laws of Universal Gravitation.
<h2>2. Right answer: Aristotelian
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Aristotle mistakenly thought that the Earth was the center of the universe, thus establishing a <u>geocentric cosmological model.
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According to this model, Aristotle proposed that the universe (the cosmos) was spherical and finite, with the Earth immobile at its center, composed of the four fundamental elements (made up of spherical layers): ground, water, air and fire; and the Sun along with the fixed planets in their respective concentric spheres revolving around the Earth. The outermost sphere being that of the stars and all these external elements being made of a fifth element which he called ether.
The amount of grams of hydrogen that are in the water sample is;
3.985 g
<h3>Avogadro's number</h3>
We are given that;
Number of moles of oxygen in a sample of water = 12 × 10²³
- Now, the chemical formula of a molecule of water is H₂O. This means that for every 1 atom or molecule of oxygen, there must be 2 hydrogen atoms or molecules present.
Since Number of moles of oxygen in the sample is 12 × 10²³, then number of moles of hydrogen will be twice that = 2 × 12 × 10²³ = 24 × 10²³ moles
Now, molar mass of hydrogen is 1 g/mol and we know that;
Molar mass = Avogadro's number(6.023 × 10²³) moles
Thus;
6.023 × 10²³ moles = 1 g/mol
Thus; 24 × 10²³ moles of hydrogen = ( 24 × 10²³ × 1)/(6.023 × 10²³)
⇒ 3.985 g
Read more on Avogadro's number at; brainly.com/question/914267
2 kg = 2000g
15 minutes + 25min (4) = 115 minutes
Answer: 1 hour and 55 min
