Scientists have changed the model of the atom as they have gathered new evidence. One of the atomic models is shown below. A purple center outlined in black with two concentric black circles around the center, the inner circle having 2 small green balls on it and the outer circle having 8 small green balls on it. What experimental evidence led scientists to change from the previous model to this one? A few of the positive particles aimed at a gold foil seemed to bounce back. The colors of light emitted from heated atoms had very specific energies. Experiments with water vapor showed that elements combine in specific proportions. Cathode rays were bent in the same way whenever a magnet was brought near them.

Answer:

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

[tex]n = \frac{N}{L} \\ [/tex]

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question we have

[tex]n = \frac{2.39 \times {10}^{23} }{6.02 \times {10}^{23} } \\ = 0.39700996...[/tex]

We have the final answer as

Hope this helps you

Answer:

D

Explanation:

Option D gives the correct model of C7H16. From the option, one will discover that the model has 7 carbons in the backbone. If you count the attached hydrogen, you will discover that the hydrogen is 16 in total.

This model or skeletal structure of this element represents heptane. Heptane or n-heptane is known to be a straight-chain compound and an alkane. It's chemical formula can also be written as: H₃C(CH₂)₅CH₃ or C₇H₁₆.

This compound is known to be one of the main components of gasoline. It is known to be a volatile organic compound and a clear and colorless liquids with a petroleum-like odor.

Answer: D

Explanation: Just took the test

Answer:

/D/ either absorbs or releases energy

Explanation:

During a phase change energy is either absorbed or released.

A phase change is a reversible process which occurs when a substance changes is its state from one form to another.

Phase changes are used to delineate physical changes.

Answer:

In physics, a force is any interaction that, when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity (which includes beginning moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a push or a pull.

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Answer:

The correct option is;

(B) [tex]\Delta H_{mix} < 0[/tex], solution shows negative deviation

Explanation:

The given parameters are;

The available volume of liquid A = 25 cm³

The available volume of liquid B = 20 cm³

The volume of the solution (mixture) = 44.8 cm³

Therefore, we have;

[tex]\Delta _{mix} V < 0[/tex]

Which is one of the prerequisite for the formation of negative deviation

When a non-ideal solution shows negative deviation according to Raoult's Law, we have;

[tex]\Delta _{mix} H < 0[/tex], we have more heat released due to new molecular interactions.

Answer:

D all above yes I think it's all above

Answer:  D

Explanation: All of the above.

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