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2 years ago

Question 3 of 25

1 answer:

Colt1911 [192]2 years ago

8 0

The statement that describes a question that can guide the design of a scientific investigation could be about the necessity of a controlled variable. The correct answer is A.

<h3>What is a controlled variable?</h3>

It is a variable whose values are controlled by the researcher during the course of experimental investigations.

When designing an experiment, it is necessary to identify the different variables that would be involved for a successful investigation.

Variables can be independent, dependent, controlled, or constant. Identifying the necessary variables will help in designing the experiment.

More on variables can be found here: brainly.com/question/15740935

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Explain how movements along faults generate earthquakes<br><br><br>

Scrat [10]

Explanation:

When a plate moves it shifts the earth, and it can cause an earthquake.

A fault is where two of earth's tectonic plates come together. They can slide against the other, causing earthquakes, they can push against each other causing mountains to form, and they can move apart from each other, causing valleys or trenches.

8 0

3 years ago

To break the oxygen-oxygen bonds in a single O2 molecule, 1 × 10–18 J of energy is required. Which of the following wavelengths

Sonbull [250]

E = hc/(lamda)

The lamda symbol is wavelength, which this site does not have. I can represent it with an "x" instead.

Plancks constant, h = 6.626×10^-32 J·s

Speed of light, c = 3.00×10^8 m/s

The energy must be greater than or equal to 1×10^-18 J

1×10^-18 J ≤ (6.626×10^-32 J·s)*(3.0×10^8 m/s) / x

x ≤ (6.626×10^-32 J·s)*(3.0×10^8 m/s) / (1×10^-18 J)

x ≤ 1.99×10^-7 m or 199 nm

The wavelength of light must be greater than or equal to 199 nm

8 0

3 years ago

A hypothetical element has an atomic weight of 48.68 amu. It consists of three isotopes having masses of 47.00 amu, 48.00 amu, a

Morgarella [4.7K]

Answer : The percent abundance of the heaviest isotope is, 78 %

Explanation :

Average atomic mass of an element is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.

Formula used to calculate average atomic mass follows:

$\text{Average atomic mass }=\sum_{i=1}^n\text{(Atomic mass of an isotopes)}_i\times \text{(Fractional abundance})_i$

As we are given that,

Average atomic mass = 48.68 amu

Mass of heaviest-weight isotope = 49.00 amu

Let the percentage abundance of heaviest-weight isotope = x %

Fractional abundance of heaviest-weight isotope = $\frac{x}{100}$

Mass of lightest-weight isotope = 47.00 amu

Percentage abundance of lightest-weight isotope = 10 %

Fractional abundance of lightest-weight isotope = $\frac{10}{100}$

Mass of middle-weight isotope = 48.00 amu

Percentage abundance of middle-weight isotope = [100 - (x + 10)] % = (90 - x) %

Fractional abundance of middle-weight isotope = $\frac{(90-x)}{100}$

Now put all the given values in above formula, we get:

$48.68=[(47.0\times \frac{10}{100})+(48.0\times \frac{(90-x)}{100})+(49.0\times \frac{x}{100})]$

$x=78\%$

Therefore, the percent abundance of the heaviest isotope is, 78 %

5 0

3 years ago

Read 2 more answers

A gas occupies the volume of 215ml at 15C and 86.4kPa?

kherson [118]

Answer:

About 0.1738 liters

Explanation:

Using the formula PV=nRT, where p represents pressure in atmospheres, v represents volume in liters, n represents the number of moles of ideal gas, R represents the ideal gas constant, and T represents the temperature in kelvin, you can solve this problem. But first, you need to convert to the proper units. 215ml=0.215L, 86.4kPa is about 0.8527 atmospheres, and 15C is 288K. Plugging this into the equation, you get:

$0.8527\cdot 0.215=n \cdot 0.0821 \cdot 288\\n\approx 7.754 \cdot 10^{-3}$