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Alex
3 years ago
6

Can you help me answer this plz

Chemistry
1 answer:
Zigmanuir [339]3 years ago
3 0

Answer: In Galileo’s time, what was considered the “center of everything”? The Earth! All of the planets and even the Sun went around “us”. Of course, when Galileo saw the moons of Jupiter passing in front of the planet, and disappearing to show up again, it was clear to him that these moons went around Jupiter like our moon goes ‘round the Earth.

That did not set well with the Beliefs of the day, and that is at least one answer!

Explanation:

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Where does the peak intensity need to fall on the spectrum for a very intense star?
viva [34]

Answer:

Gamma range

Explanation:

A very intense start is a bright star at very high temperature. Now, hotter the object shorter is the wavelength of peak radiation. The increasing order of wavelength of the given regions in the electromagnetic spectrum are:

gamma range < ultra violet < visible < infrared

Ideally, since the shortest wavelength based on the given options is the gamma range, the peak intensity can also be expected to fall at that wavelength. If the star spectrum was recorded in the UV-visible range of the EM spectrum, then it would fall in the UV range

7 0
3 years ago
Read 2 more answers
Hard water often contains dissolved Mg2+and Ca2+ions. Water softeners often use sodium carbonate to soften the water. Sodium car
Dvinal [7]

Answer:

32.5g of sodium carbonate

Explanation:

Reaction of sodium carbonate (Na₂CO₃) with Mg²⁺ and Ca²⁺ as follows:

Na₂CO₃(aq) + Ca²⁺(aq) → CaCO₃(s)

Na₂CO₃(aq) + Mg²⁺(aq) → MgCO₃(s)

<em>1 mole of carbonate reacts per mole of the cations.</em>

<em />

To know the mass of sodium carbonate we must know the moles of carbonate we need to add based on the moles of the cations:

<em>Moles Mg²⁺:</em>

2.91L * (0.0661 moles MgCl₂ / 1L) = 0.192 moles MgCl₂ = Moles Mg²⁺

<em>Moles Ca²⁺:</em>

2.91L * (0.0396mol Ca(NO₃)₂ / 1L) = 0.115 moles Ca(NO₃)₂ = Moles Ca²⁺

That means moles of sodium carbonate you must add are:

0.192 moles + 0.115 moles = 0.307 moles sodium carbonate.

In grams (Using molar mass Na₂CO₃ = 105.99g/mol):

0.307 moles Na₂CO₃ * (105.99g / mol) =

<h3>32.5g of sodium carbonate</h3>
3 0
3 years ago
Simple question ill name u brainiest
BigorU [14]

Answer:

Test tube :)

Explanation:

4 0
3 years ago
Read 2 more answers
Which evidence is an indication that a chemical reaction has occurred?
Luden [163]

Answer:

  • Some signs of a chemical change are a change in color and the formation of bubbles. The five conditions of chemical change: color change, formation of a precipitate, formation of a gas, odor change, temperature change.

8 0
2 years ago
Only radioactive isotopes are useful for radiometric dating or medical diagnostic exams. Briefly explain why stable isotopes wou
Mnenie [13.5K]

Answer:

Explanation:

Isotopes are atoms of elements that have the same atomic number but different mass number hence ISOTOPY. Radioactive Isotopes on the other hand are unstable as they either undergo Alpha decay, beta decay or gamma decay compared to stable isotopes.

Radioactive elements decay at varyinf rates as such the rate of radioactive decay is used in the characterization of radioactive element and mostly expressed in terms of the half life of the radioactive elements.

Half life is the time taken for half of the total atoms of an elements to decay into half of its initial sizes. for example, the half life of radium-226 is 1622 years, it implies that if we have 1000000 radium atoms at the beginning, then at the end of 1622years, 500000 would have disintegrated. These phenomenon can never be experienced by stable isotopes as such they can not be used in carbon dating techniques. reason why uranium-238 is mostly and commonly used in the earth crust to estimate the ages of rocks because it has a half life of 4.5 x 10^9 years.

And also, the radioactive isotopes of most common light element are short, they have very short half life (few days or weeks) and they decay rapidly to vanshing point, as such, they are not found in nature to any reasonable extent.

8 0
3 years ago
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