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sashaice [31]
4 years ago
5

REALLY NEED HELP FAST

Chemistry
1 answer:
Georgia [21]4 years ago
5 0
The first and third. The indivisibility of an atom was proved wrong because an atom can be subdivided into protons, neutrons and electrons. And subatomic particles take part in chemical reactions. Atoms of some elements vary in their masses/densities which are isotopes. Dalton also claimed that atoms of different elements are different which can be wrong in certain cases, such as argon and calcium.
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Name three stars that are hotter than the sun
devlian [24]

Eta Carinae could be as large as 180 times the radius of the Sun, and its surface temperature is 36,000-40,000 Kelvin. Just for comparison, 40,000 Kelvin is about 72,000 degrees F. So it's the blue hypergiants, like Eta Carinae, which are probably the hottest stars in the Universe.

7 0
4 years ago
1) Which of the following is the best example of a physical change?
never [62]

1 is b and 2 is also b

4 0
4 years ago
Copper is an example of a(n) __________.
navik [9.2K]
The answer is D. element

It's not a mixture, just a pure element. Copper (Cu) is found on the Periodic Table of the Elements, where only ELEMENTS are organized.
7 0
3 years ago
Read 2 more answers
What is the mean free path for the molecules in an ideal gas when the pressure is 100 kPa and the temperature is 300 K given tha
sladkih [1.3K]

Answer:

The mean free path = 2.16*10^-6 m

Explanation:

<u>Given:</u>

Pressure of gas P = 100 kPa

Temperature T = 300 K

collision cross section, σ = 2.0*10^-20 m2

Boltzmann constant, k = 1.38*10^-23 J/K

<u>To determine:</u>

The mean free path, λ

<u>Calculation:</u>

The mean free path is related to the collision cross section by the following equation:

\lambda =\frac{1}{n\sigma }------(1)

where n = number density

n = \frac{P}{kT}-----(2)

Substituting for P, k and T in equation (2) gives:

n = \frac{100,000 Pa}{1.38*10^{-23} J/K*300K} =2.42*10^{25}\  m^{3}

Next, substituting for n and σ in equation (1) gives:

\lambda =\frac{1}{2.42*10^{25}m^{-3}* .0*10^{-20}m^{2}}=2.1*10^{-6}m

6 0
3 years ago
A sample of oxide iron weighing 2.40g was heated in a stream of hydrogen until it was completely converted to the metal. If the
wlad13 [49]

Answer:

Fe₂O₃

Explanation:

To solve this question we must find the moles of Iron in 1.68g. With the difference of the masses we can find the moles of oxygen. The formula will be obtained with the ratio of both amount of moles:

<em>Moles Fe:</em>

1.68g * (1mol / 56g)  =0.03moles

<em>Moles O:</em>

2.40g-1.68g = 0.72g * (1mol/16g) = 0.045moles

The ratio O/Fe is:

0.045moles / 0.03moles = 1.5 moles. this ratio is obtained if the formula is:

<h3>Fe₂O₃</h3>
4 0
4 years ago
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