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2 years ago

5

An exciton is: A charged particle made of electrons A charged particle made of holes A neutral particle made of an electron and

hole A photon in an excited state

1 answer:

Alex2 years ago

7 0

Answer:

A neutral particle made of an electron and hole

Explanation:

Exciton

It is the combination of an electron and a hole ( hole refers to the vacancy of an electron ) . And , as both the electron and the hole have the same charge but the polarity is opposite , the combination will lead to a neutral compound , i.e. , Exciton have no charge and so neutral .

It is free to move in the nonmetallic crystal and since it charge less , it is difficult to detect it directly .

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Which of the following units would be the most appropriate for measuring the thickness of a piece of paper? A. centimeters B. mi

Alla [95]

B, millimeters because paper is really thin therefore it'd require small measurements for units.

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3 years ago

How has Charles Darwin contributed to the study of evolution?

Lunna [17]

Do you answer is he proposed a genetic relationship between species

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2 years ago

Carry out the following operations as if they were calculations of experimental results and express each answer in standard nota

Shalnov [3]

Answer:

1. $10.6\; \rm m$ (one decimal place.)

2. $0.79\; \rm g$ (two decimal places.)

3. $16.5\;\rm cm^2$ (three significant figures.)

Explanation:

<h3>1.</h3>

The first and second expressions are additions and subtractions. When adding two numbers, the accuracy of the result is given by the number of decimal places in it. The result should have as many decimal places as the input with the least number of decimal places.

For example, in the first expression:

$5.6792\;\rm m$ has four decimal places.
$0.6\; \rm m$ has only one decimal place.
$4.33\; \rm m$ has two decimal places.

Therefore, the result should be rounded to one decimal place. Note that these units are compatible for addition, since they are all the same. The result should have the same unit (that is: $\rm m$ .)

Therefore:

$\rm 5.6792\; m + 0.6\; m + 4.33\; m \approx 10.6\; \rm m$ . (Rounded to one decimal place.)

<h3>2.</h3>

Similarly:

$\rm 3.70\; \rm g$ has two decimal places.
$2.9133\; \rm g$ has four decimal places.

Therefore, the result should be rounded to two decimal places. Its unit should be $\rm g$ (same as the unit of the two inputs.)

$\rm 3.70\; g - 2.9133\; g \approx 0.79\; \rm g$ . (Rounded to two decimal places.)

<h3>3.</h3>

When multiplying two numbers, the accuracy of the result should be based on the number of significant figures in it. The result should have as many significant figures as the input with the least number of significant figures. In this expression:

$4.51\; \rm cm$ has three significant figures.
$3.6666\; \rm cm$ has five significant figures.

Therefore, the result should have only three significant figures.

The unit of the result is supposed to be the product of the units of the input. In this expression, that unit will be $\rm cm \cdot cm$ , which is occasionally written as $\rm cm^2$ .

$\rm 4.51 \; cm \times 3.6666 \; cm \approx 16.5\; \rm cm^2$ . (Rounded to three significant figures.)

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3 years ago

How many nitrogen atoms are in the chemical formula below? C8H10(N4O2)2

Elena L [17]

Answer:

8 Nitrogen atoms

Explanation:

Step 1: Define

Chemical Formula - C₈H₁₀(N₄O₂)₂

Step 2: Multiply

(N₄)₂ = N₈

4 0

3 years ago

A chemical reaction produces 5.6l of nitrous oxide gas what is the mass of the gas produced

jonny [76]

<u>Answer:</u> The mass of the nitrous oxide gas produced is 0.011 kg.

<u>Explanation:</u>

To calculate the mass of the gas, we use the formula:

$Density=\frac{Mass}{Volume}$

We are given:

Specific density of the gas = $1.98kg/m^3$

Mass of the gas = ? kg

Volume of the gas = $5.6L=0.0056m^3$ (Conversion Factor: $1m^3=1000liters$ )

Putting values in above equation, we get:

$1.98kg/m^3=\frac{Mass}{0.0056m^3}$

$Mass=0.011kg$

Hence, the mass of the nitrous oxide gas produced is 0.011 kg.

7 0

2 years ago