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emmainna [20.7K]
3 years ago
9

What is the name of the phase where stars live out most of their lives?

Chemistry
1 answer:
lisov135 [29]3 years ago
8 0
The correct option is B. 
Stars live out most of their lives at MAIN SEQUENCE. Stars generally are divided into three major stages, these are:
1. Pro stars and pre-main sequence star
2. Main sequence  and giant star
3. Variable stars
Major stages in the life of a star can last for millions of years.

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Which of the following statements is incorrect? A. Molecular mass is expressed in atomic mass units. B. Formula mass compares th
n200080 [17]

Answer:

  • The incorrect statement is the choice <em>C. Atomic mass has units of grams per atom.</em>

Explanation:

<u>1) Choice A.</u><em><u> Molecular mass is expressed in atomic mass units</u></em><u>.</u>

Correct. Atomic mass units (a.m.u) is the standard unit used to express the mass of the atoms and the molecules.

Since, one atom, molecule, or formula unit is a tiny amount of material, it has a ver, very low mass, and the unit mass of a molecule is referred to one mole (6.022 × 10²³ units).

<u>2) Choice B. </u><em><u>Formula mass compares the mass of one formula unit of a substance to the mass of one atom of carbon-12</u></em><u>.</u>

Correct. The masses of atoms and compounds are referred to a standard. Such standard is the carbon-12 atom. This is, the cabon-12 atom was selected as the standard and its exact mass is 12 a.m.u.

<u>3)  Choice C. </u><em><u>Atomic mass has units of grams per atom.</u></em><u> </u>

Incorrect. Atomic mass is the mass of the atoms, but, since, the mass of one atom is so small, the atomic mass is referred to one mole. Hence, the atomic mass has units of grams per mole.

<u>4) Choice D. </u><em><u>Both molecular mass and formula mass use carbon-12 as a reference standard.</u></em>

Correct. As stated when explaining the option B, the mass of atoms, molecules, and formula units are referred to carbon-12 standard.

<u>5) Choice E. S</u><em><u>odium chloride, an ionic compound, is said to have a formula weight, but not a molecular weight.</u></em>

Correct. The reason is that ionic compounds form large structures (crystals) and, since there is not such thing as one molecule of them, they are said to have formula weight (or mass) but not a molecular weight.

The name molecules is reserved for covalent compounds, where you can formally identify molecules. E.g. Water is a molecular compound, and each molecule has molecular formula H₂O, whose mass is the molecular mass.

7 0
3 years ago
Calcium ions are removed from the sarcoplasm of the cardiac cell by the action of the sarcoplasmic reticulum (SR) Ca2+-ATPase pu
Ivan

Answer:

Sodium-calcium exchanger on the sarcolemma

Explanation:

The sodium-calcium exchanger which is an antiporter membrane protein, removes calcium from cells. The energy of the electrochemical gradient of sodium is used by allowing it to flow down its gradient while moving across the plasma membrane

7 0
3 years ago
You are testing an unknown liquid to determine its identity. First you heat the liquid and find that it turns to gas at 80 degre
SVETLANKA909090 [29]

Answer: The answer is <u><em>(Boiling Point) </em></u>:)

<u><em /></u>

7 0
3 years ago
James was standing on a boat in deep ocean water. He wanted to see how long it would take a tennis ball to reach the shore if he
Black_prince [1.1K]

Answer:

only the wave energy of the water moves

Explanation:

The plan will not work due to the fact that only the wave energy of the water moves and not the water itself.

<em>The wave motion of water does not displace the water. It is only able to transfer energy from one point to another within the medium. Hence, the ball will hardly be displaced because the water itself does not move. However, it can get to the shore with the assistance of the water current.</em>

7 0
3 years ago
Indicate the number of unpaired electrons for following:
Viktor [21]
Ignoring the n's, there would only be one unpaired electron. 
6 0
3 years ago
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