Which element has their valence electron farthest from the nucleus?

Which of these statements about natural selection is true? (Select all that apply.)

ira [324]

Answer:

The Answer is A.

Explanation:

Dont judge me if I'm wrong. I'm new to Brainly.

8 0

3 years ago

Liquid octane will react with gaseous oxygen to produce gaseous carbon dioxide and gaseous water . Suppose 97. g of octane is mi

zhannawk [14.2K]

Answer: 61 grams

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles of octane}=\frac{\text{Given mass}}{\text{Molar mass}}=\frac{97g}{114g/mol}=0.85moles$

$\text{Number of moles of oxygen}=\frac{\text{Given mass}}{\text{Molar mass}}=\frac{150g}{32g/mol}=4.69moles$

The chemical equation for the combustion of octane in oxygen follows the equation:

$2C_8H_{18}+25O_2\rightarrow 16CO_2+18H_2O$

By stoichiometry of the reaction;

25 moles of oxygen react with 2 moles of octane

4.69 moles of oxygen react with= $\frac{2}{25}\times 4.69=0.37$ moles of octane

Thus, oxygen is the limiting reagent as it limits the formation of product and octane is the excess reagent.

25 moles of oxygen produce 18 moles of water

4.69 moles of oxygen produce= $\frac{18}{25}\times 4.69=3.38$ moles of water.

Mass of water produced= $moles\times {\text{Molar mass}}=3.38\times 18g/mol=61g$

The maximum mass of water that could be produced by the chemical reaction is 61 grams.

6 0

3 years ago

Why is it important to use standard measurements and units in science

saul85 [17]

Unit' is the word used to describe how something is measured. When researching a question in science, we collect data, interpret it, and share the results with other scientists. A common measurement system allows us to make direct comparisons instead of having to know things like how much a certain animal weighs.

6 0

3 years ago

Which equation is used to help form the combined gas law?

kkurt [141]

Answer:

The ideal gas equation

Explanation:

The ideal gas equation is derived from the combination of three gas laws:

Boyle's law
Charles's law
Avogadro's law.

The ideal gas law is expressed mathematically as: PV=nRT where:

P is pressure

V is volume

n is the number of moles

R is the ideal gas law

T is temperature.

To obtain the combined gas law, we assume that n=1 and this gives:

$\frac{PV}{T}$ = R

Therefore:

$\frac{P_{1} V_{1} }{T_{1} }$ = $\frac{P_{2} V_{2} }{T_{2} }$

5 0

3 years ago

If the accepted value for the mass of an object is 20.0g and the student found that the mass of the object was 20.5g what is the

NikAS [45]

Answer:

Results

The percent error between 20 and 20.5 is 2.5%

Explanation:

Percent Error = | (20.5 − 20) / 20 | × 100 = | (0.5) / 20 | × 100 = | 0.025 | × 100 = 2.5% (three decimal places)Percent Error = 2.5%

3 0

3 years ago