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2 years ago

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A star is mainly made of hydrogen gas, but most classes of stars include other elements such as helium, calcium, and other heavi

er elements and molecules.
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True

False

2 answers:

Xelga [282]2 years ago

6 0

That would be true, since most other stats include helium, calcium, etc

Sidana [21]2 years ago

4 0

The answer is true! :)

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Which is the metric standard for measuring energy? Which unit is used for specific heat capacity? If you wanted to compare the a

DENIUS [597]

1. Which is the metric standard for measuring energy?

The <u>metric standard for measuring of energy </u>defined by the International System of Units is the joule (J), which is defined as the work done by a force of a newton in a displacement of one meter in the direction of force. So,

1 J = 1 N m = 1 kg·m²/s²

Calorie is also frequently used in scientific and technological applications. Calorie is a <u>unit of thermal energy that is equivalent to the amount of heat needed to raise the temperature of 1 gram of water by 1 degree Celsius</u>.

1 cal = 4,184 J

2. Which unit is used for specific heat capacity?

The specific heat capacity (c) is a physical quantity that is defined as the <u>amount of heat (</u><u>q</u><u>) that must be supplied to the mass unit of a thermodynamic substance or system to raise its temperature by one unit.</u> So,

c = q / m ΔT

where m is the mass of the substance and ΔT is the temperature increase.

In this way, as heat is a form of energy, the International System of Units expresses the specific heat in <u>joules per kilogram and per kelvin</u> (J kg⁻¹ K⁻¹). Another common unit, not belonging to the SI, is the <u>calorie per gram and per degree centigrade</u> (cal g⁻¹ ° C⁻¹).

3. If you wanted to compare the abilities of olive oil and peanut oil to gain or lose thermal energy, which unit would you use?

You should use units of specific heat capacity (J kg⁻¹ K⁻¹) since, as mentioned above, this is a physical quantity that measures the amount of heat that must be supplied to an specific mass of a substance or system to raise its temperature.

Heat is a thermal energy, so <u>by using heat capacity units you can compare the ability of</u><u> </u><u>olive oil and peanut oil to gain or lose thermal energy by varying its temperature.</u>

3 0

3 years ago

Read 2 more answers

Which statement correctly describes two forms of oxygen, O2 and O3?

fgiga [73]

The two forms of oxygen, O2 and O3 is "<span>They have different molecular structures and different properties."</span>

7 0

3 years ago

Read 2 more answers

Without the sun, life on earth would not exist. There would be no warmth, no plants, no animals, no night and day.

zvonat [6]

Answer: Option (A) is the correct answer.

Explanation:

The process in which two or more small nuclei combine together to result in the formation of a larger nuclei is known as fusion.

In Sun, four hydrogen nuclei combine together to result in the formation of helium atom. This combining of small hydrogen nuclei to form a large helium nuclei represents fusion process occurring inside the Sun.

Thus, we can conclude that to power itself, the sun is constantly generating a nuclear reaction in its core, in which hydrogen nuclei are combined to form helium. This process is known as fusion.

7 0

3 years ago

Read 2 more answers

The substance that waves travel though?

Sedaia [141]

C) medium.

The medium of a wave is any substance that carries the wave, or through which the wave travels.Ocean waves are carried by water, sound waves are carried by air, and. the seismic waves of an earthquake are carried by rock and soil.

5 0

3 years ago

Identify the most acidic hydrogens in each of the following molecules. Give the structure of the enolate ion arising from deprot

san4es73 [151]

Answer:

See explanation below (Brainlist please)

Explanation:

First of all, we need to understand what is an acidic hydrogen.

An acidic hydrogen, is the atom of hydrogen which is more propense to undergo an acid base reaction, and form a stable ion or molecule in the process.

In other words, is the hydrogen that is more vulnerable to get substracted in an acid base reaction to form another compound.

Knowing this information, gives us an idea of how a molecule can be formed and which kind of compound is formed.

Now, in this question, we have 5 molecules. Each of them is either a ketone or aldehyde, so this mean that we have the carbonile group (C = O), which means that is easier to identify the acidic hydrogen. This is because the Carbonile group is an attractor group, so, it will attract the charges by inductive effect (in some cases by resonance), and the molecule is more stable.

This can be shown by drawing the enolate ion that is formed once the molecule undergo the acid base reaction. As it's an enolate form that we are looking for, then it means that the ketone or aldehyde is undergoing an electrofilic attack with a base. This base will substract the most acidic hydrogen to form a better and stable enolate. The acidic hydrogen and the enolate form can be seen in the attached picture.

a) In the case of acetaldehyde, the most acidic will be the hydrogen of carbon 2, because the hydrogen from the carbonile, once it's substracted, the charge of the carbon cannot be stabilized by resonance. Carbon 2 hydrogens, can do this job easily.

b) Propanal happens something similar to acetaldehyde, the terminal hydrogen cannot be substracted, and carbon 3, once the hydrogen is gone, the negative charge cannot be stabilized by resonance, so hydrogens of carbon 2 can do this.

c) in the case of acetone, is easier to look because we only have the C = O between two methyl group, so you can use either carbon 1 or 3 to do the job.

d) 4 heptanone the most acidic hydrogen would be carbon 3 or 5, because they are closer to the C=O and the ion can be stabilized by resonance.

e) Finally in ciclopentanone, the most acidic hydrogen would be carbon 2 or 5.

See picture for a better understanding.

Hope it helps.

7 0

3 years ago