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3 years ago

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A sample of metal is heated until it melts and begins to glow red. When it cools, it appears the same color as it did before it

was heated. This is evidence that a chemical reaction occurred. is it true or false

1 answer:

frosja888 [35]3 years ago

8 0

Answer:

Explanation:

trueeeeeeeeeeeeeeeeeeeeeeeeeee

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All of these are examples of an animal maintaining homeostasis EXCEPT:

Pie

Answer:

A whale bleeding from a cut.

Explanation:

Shivering in the cold, breathing hard during exercise, and sweating because it's hot are ways the body is working to maintain good functioning and to keep the body alive. Bleeding from a cut is not an example of this.

3 0

3 years ago

Consider 100.0 g samples of two different compounds consisting only of carbon and oxygen. One compound contains 27.2 g of carbon

Pani-rosa [81]

<u>Answer:</u> The ratio of carbon in both the compounds is 1 : 2

<u>Explanation:</u>

Law of multiple proportions states that when two elements combine to form two or more compounds in more than one proportion. The mass of one element that combine with a given mass of the other element are present in the ratios of small whole number. For Example: $Cu_2O\text{ and }CuO$

<u>For Sample 1:</u>

Total mass of sample = 100 g

Mass of carbon = 27.2 g

Mass of oxygen = (100 - 27.7) = 72.8 g

To formulate the formula of the compound, we need to follow some steps:

<u>Step 1:</u> Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{27.2g}{12g/mole}=2.26moles$

Moles of Oxygen = $\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{72.8g}{16g/mole}=4.55moles$

<u>Step 2:</u> Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 2.26 moles.

For Carbon = $\frac{2.26}{2.26}=1$

For Oxygen = $\frac{4.55}{2.26}=2.01\approx 2$

<u>Step 3:</u> Taking the mole ratio as their subscripts.

The ratio of C : O = 1 : 2

Hence, the formula for sample 1 is $CO_2$

<u>For Sample 2:</u>

Total mass of sample = 100 g

Mass of carbon = 42.9 g

Mass of oxygen = (100 - 42.9) = 57.1 g

To formulate the formula of the compound, we need to follow some steps:

<u>Step 1:</u> Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{42.9g}{12g/mole}=3.57moles$

Moles of Oxygen = $\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{57.1g}{16g/mole}=3.57moles$

<u>Step 2:</u> Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 3.57 moles.

For Carbon = $\frac{3.57}{3.57}=1$

For Oxygen = $\frac{3.57}{3.57}=1$

<u>Step 3:</u> Taking the mole ratio as their subscripts.

The ratio of C : O = 1 : 1

Hence, the formula for sample 1 is $CO$

In the given samples, we need to fix the ratio of oxygen atoms.

So, in sample one, the atom ratio of oxygen and carbon is 2 : 1.

Thus, for 1 atom of oxygen, the atoms of carbon required will be = $\frac{1}{2}\times 1=\frac{1}{2}$

Now, taking the ratio of carbon atoms in both the samples, we get:

$C_1:C_2=\frac{1}{2}:1=1:2$

Hence, the ratio of carbon in both the compounds is 1 : 2

8 0

3 years ago

How many protons are in an element with an atomic number of 8 and a mass of 18?

Pachacha [2.7K]

B: 8 the amount of protons is equal to the atomic number

4 0

3 years ago

Read 2 more answers

A 15.0 L tank of gas is contained at a high pressure of 8.20 x 10^4 torr. The tank is opened and the gas expands into an empty c

Inga [223]

Answer:

20.5torr

Explanation:

Given parameters:

V₁ = 15L

P₁ = 8.2 x 10⁴torr

V₂ = 6 x 10⁴L

Unknown:

P₂ = ?

Solution:

To solve this problem we have to apply the claims of Boyle's law.

Boyle's law is given mathematically as;

P₁ V₁ = P₂V₂

where P₁ is the initial pressure

V₁ is the initial volume

P₂ is final pressure

V₂ is final volume

8.2 x 10⁴ x 15 = P₂ x 6 x 10⁴

P₂ = 20.5torr

5 0

3 years ago

What is the molar mass of CaCl2?

alekssr [168]

Molar mass of CaCl2 = 40+ ( 35.5 ×2)=110

Mr of Ca(OH)2 = 40+ (16+1)×2 =74

%of Ca = (40÷ 74)×10=...

1 m = 100cm...
1cm = (1÷100) m
So 45.5 cm = 45.5 ×(1÷100) =....

1km = 1000m
1m = 100 cm
1cm =10mm
So 1km = 1000×100×10 mm
Now convert

7 0

3 years ago