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3 years ago

HELP PLEASE! I WILL GIVE YOU POINTS

Chemistry

2 answers:

scoundrel [369]3 years ago

8 0

A. An Interdependent system of plants, animals, and land

maw [93]3 years ago

7 0

I would say A is the best answer

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Question 2 of 10

Ganezh [65]

I think A. Molecules interact without bonds breaking

8 0

2 years ago

The element iridium exists in nature as two isotopes: 191Ir has a mass of 190.9606 u, and 193Ir has a mass of 192.9629 u. The av

nlexa [21]

Answer: The percentage abundance of $_{77}^{191}\textrm{Ir}$ and $_{77}^{193}\textrm{Ir}$ isotopes are 37.10% and 62.90% respectively.

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:

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

Let the fractional abundance of $_{77}^{191}\textrm{Ir}$ isotope be 'x'. So, fractional abundance of $_{77}^{193}\textrm{Ir}$ isotope will be '1 - x'

For $_{77}^{191}\textrm{Ir}$ isotope:

Mass of $_{77}^{191}\textrm{Ir}$ isotope = 190.9606 amu

Fractional abundance of $_{77}^{191}\textrm{Ir}$ isotope = x

For $_{77}^{193}\textrm{Ir}$ isotope:

Mass of $_{77}^{193}\textrm{Ir}$ isotope = 192.9629 amu

Fractional abundance of $_{77}^{193}\textrm{Ir}$ isotope = 1 - x

Average atomic mass of iridium = 192.22 amu

Putting values in equation 1, we get:

$192.22=[(190.9606\times x)+(192.9629\times (1-x))]\\\\x=0.3710$

Percentage abundance of $_{77}^{191}\textrm{Ir}$ isotope = $0.3710\times 100=37.10\%$

Percentage abundance of $_{77}^{193}\textrm{Ir}$ isotope = $(1-0.3710)=0.6290\times 100=62.90\%$

Hence, the percentage abundance of $_{77}^{191}\textrm{Ir}$ and $_{77}^{193}\textrm{Ir}$ isotopes are 37.10% and 62.90% respectively.

8 0

3 years ago

Please Help!!!

Talja [164]

Answer:

The mechanical energy produced on burning fossil fuels is transformed into chemical energy stored in carbon dioxide.

Explanation:

When fossil fuels are burnt, mechanical energy is produced. Remember that according to the first law of thermodynamics, energy is neither created nor destroyed but can be transformed from one form to another. Hence the mechanical energy produced when fossil fuels are burnt for industrial use, heating of homes, electricity generation , cooking etc the mechanical energy produced is not 'lost'. It must be transformed in to another form of energy.

In the image the arrow G----> C, shows the mechanical energy produced when fossil fuels are burnt are stored as chemical energy in CO2 bonds. CO2 is found in the atmosphere, hence the arrow point upwards from the source towards the atmosphere (C is the atmospheric reservoir of CO2). The energy is subsequently used by producers to produce chemical energy stored in food.

6 0

3 years ago

Calculate the answer. Express it in scientific notation. All answers should have the correct number of significant figures.

beks73 [17]

(1.632) (4.0 x 104)

= (1.632)(416)

=678.912

6.8* 10^2.

Not sure if it's the right sig figs.

8 0

3 years ago

Read 2 more answers

How many grams of O2 are required for the complete reaction of 45.0g of CH4 to form CO2 and H2O?

Wewaii [24]

Answer: 90 g O2

Explanation: soution attached:

Balance first the chemical equation

CH4 + O2 => CO2 +2H2O

Convert mass of CH4 to moles

Use the mole ratio of CH4 and O2 from the balanced equation.

Convert moles of O2 to mass using the molar mass of O2.

6 0

3 years ago