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2 years ago

Why are mole ratios important in stoichiometry?

1 answer:

8 0

Mole ratios<span> are important because mole ratios allow you change moles of a substance to moles of another substance.</span>

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Claude Bernard first recognized _____.

storchak [24]

Answer : Option B) Plant stomata opening and closing to maintain homeostasis.

Explanation : Claude Bernand was a French Physiologist who first discovered about "homeostasis" which is defined as the controlled stability of the internal milieu, or internal environment, of cells and tissues in plants.

In plants stomatal opening and closing was done for maintaining homeostasis with the external and internal plant environment.

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2 years ago

If a bouncing ball has a total energy of 20 J and a kinetic energy of 5 J, the ball’s potential energy is____J.

astra-53 [7]

Answer:If a bouncing ball has a total energy of 20 J and a kinetic energy of 5 J, the ball’s potential energy is 15J.

If the kinetic energy of the ball decreases, then the potential energy will Increase.

Explanation:

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2 years ago

What is the molarity (M) of .5 liter of a solution that has 205 g of NaCl dissolved in it?

jeka94

Answer:

<h2>Molarity = 7 mol / L</h2>

Explanation:

Since the mass of NaCl and it's volume has been given we can find the molarity by using the formula

<h3> $C = \frac{m}{M \times v}$ </h3>

where

C is the molarity

m is the mass

M is the molar mass

v is the volume

From the question

v = 0.5 L

m = 205 g

We must first find the molar mass and then substitute the values into the above formula

M( Na) = 23 , M( Cl) = 35.5

Molar mass of NaCl = 23 + 35.5 =

58.5 g/mol

So the molarity of NaCl is

$C = \frac{205}{0.5 \times 58.5} \\ C = \frac{205}{29.25}$

C = 7.00854

We have the final answer as

<h3>Molarity = 7 mol / L</h3>

Hope this helps you

8 0

2 years ago

The radioactive element carbon-14 has a half-life of 5750 years. a scientist determined that the bones from a mastodon had los

Monica [59]

Radioactive elements obey 1st order kinetics,

For 1st order reaction, relation between rate constant (k) and half life [t(1/2)] is,
k = $\frac{0.693}{t(1/2)} = \frac{0.693}{5750} = 1.205 X 10^-^4 hr^-^1$

Also, for 1st order reaction, we have
t = $\frac{2.303}{k} log \frac{\text{initial conc.}}{\text{final conc.}}$

Given that: <span>the bones from a mastodon had lost 78.5% of their C14,
</span>∴ initial conc. of C14 = 100%, conc. of C14 left after time 't' = 21.5%

∴t = $\frac{2.303}{1.205 X 10^(-4)} log \frac{\text{100}}{\text{21.5}}$ = 1.2758 X 10^4 hours

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2 years ago

A. What mass (in g) of KIO3 is needed to prepare 50.0 mL of 0.20 M KIO3?

rewona [7]

Answer:

A. 2.139g of KIO3

B. 26.67mL

Explanation:Please see attachment for explanation

3 0

2 years ago