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2 years ago

Which statements about fresh-water sources are true.? (Multiple Choice) (please help asap thanks!:)

Chemistry

1 answer:

Kay [80]2 years ago

3 0

Answer:

The correct answers are:
"Only about 3 percent of Earth's water is fresh water."

"About 75% percent of the fresh water on Earth is frozen in ice sheets."

"The largest source of usable fresh water is groundwater."

Explanation:

3 percent of Earth's water is most certainly fresh water. Confirmed with a few fact checks.

The largest source of usable fresh water on Earth is groundwater. It's more difficult to access but it's there and much more usable than water say frozen in ice on the sea.

The most correct option left would be 75% of Earth's freshwater being in ice sheets even though it's about 70%.

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FIVE TRUE/FALSE please help

marin [14]

Answer:

9. false

10. true

11. false

12. true

13. true

Explanation:

9. a Newton is the SI unit of force.

11. it says energy can't be created or destroyed

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3 years ago

How do we know what's inside an atom?

Lemur [1.5K]

Answer:

To really 'see' inside the atom and detect fundamental particles we need to go beyond visible light and bounce particles off the smallest building blocks of the Universe to 'observe' them. This session introduces students to the scientific process—how scientific methods and theories are updated and develop as new evidence and information is collected.

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3 years ago

100. mg of an unknown protein are dissolved in enough solvent to make 5.00mL of solution. The osmotic pressure of this solution

PolarNik [594]

<u>Answer:</u> The molar mass of the unknown protein is 6387.9 g/mol

<u>Explanation:</u>

To calculate the concentration of solute, we use the equation for osmotic pressure, which is:

$\pi=iMRT$

or,

$\pi=i\times \frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}\times RT$

where,

$\pi$ = osmotic pressure of the solution = 0.0766 atm

i = Van't hoff factor = 1 (for non-electrolytes)

Mass of protein = 100. mg = 0.100 g (Conversion factor: 1 g = 1000 mg)

Molar mass of protein = ?

Volume of solution = 5.00 mL

R = Gas constant = $0.0821\text{ L atm }mol^{-1}K^{-1}$

T = temperature of the solution = $25^oC=[25+273]K=298K$

Putting values in above equation, we get:

$0.0766atm=1\times \frac{0.100\times 1000}{\text{Molar mass of protein}\times 5}\times 0.0821\text{ L. atm }mol^{-1}K^{-1}\times 298K\\\\\pi=\frac{1\times 0.100\times 1000\times 0.0821\times 298}{0.0766\times 5}=6387.9g/mol$