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natima [27]
3 years ago
11

Identical rock types, identical fossils, and very similar mountain ranges are found on different continents that are separated b

y a wide ocean. Which of these best explains these observations?
A. Organisms traveled between these continents on land bridges.
B. The same forces erode mountains in different locations.
C. These continents were joined together at one time in the past.
D. Some rock types are very common and are found everywhere.
Chemistry
2 answers:
Dmitriy789 [7]3 years ago
8 0

Answer:

These continents were joined together at one time in the past.

Explanation:

Identical rock types, identical fossils, and very similar mountain ranges are found on different continents that are separated by a wide ocean. Which of these BEST explains these observations?

MrRa [10]3 years ago
6 0
These continents were joined together at one time in the past
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Floats or sinks Because of its mass
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3 years ago
How many atoms of carbon are found in a 30.0 gram sample of the element?
saveliy_v [14]

Answer:

1.50 × 10²⁴ atoms C

Explanation:

Step 1: Define

Molar mass of C - 12.01 g/mol

Avagadro's Number: 6.02 × 10²³ atoms, molecules, formula units, etc.

Step 2: Use Dimensional Analysis

30.0 \hspace{3} g \hspace{3} C(\frac{1 \hspace{3} mol \hspace{3} C}{12.01 \hspace{3} g \hspace{3} C} )(\frac{6.02(10)^{23} \hspace{3} atoms \hspace{3} C}{1 \hspace{3} mol \hspace{3} C} ) = 1.50375 × 10²⁴ atoms C

Step 3: Simplify

We are given 3 sig figs.

1.50375 × 10²⁴ atoms C ≈ 1.50 × 10²⁴ atoms C

3 0
3 years ago
Caffeine (C8H10N4O2) is a weak base with a pKb of 10.4. Calculate the pH of a solution containing a caffeine concentration of 41
RSB [31]

Answer:

pH → 7.47

Explanation:

Caffeine is a sort of amine, which is a weak base. Then, this pH should be higher than 7.

Caffeine + H₂O  ⇄  Caffeine⁺  +  OH⁻      Kb

1 mol of caffeine in water can give hydroxides and protonated caffeine.

We convert the concentration from mg/L to M

415 mg = 0.415 g

0.415 g / 194.19 g/mol = 2.14×10⁻³ mol

[Caffeine] = 2.14×10⁻³  M

Let's calculate pH. As we don't have Kb, we can obtain it from pKb.

- log Kb = pKb → 10^-pKb = Kb

10⁻¹⁰'⁴ = 3.98×10⁻¹¹

We go to equilibrium:

Caffeine + H₂O  ⇄  Caffeine⁺  +  OH⁻      Kb

Initially we have 2.14×10⁻³ moles of caffeine, so, after the equilibrium we may have (2.14×10⁻³ - x)

X will be the amount of protonated caffeine and OH⁻

     Caffeine     +    H₂O  ⇄  Caffeine⁺  +  OH⁻      Kb

   (2.14×10⁻³ - x)                         x                x

We make the expression for Kb:

3.98×10⁻¹¹ = x² / (2.14×10⁻³ - x)

We can missed the -x in denominator, because Kb it's a very small value.

So: 3.98×10⁻¹¹ = x² / 2.14×10⁻³

√(3.98×10⁻¹¹ . 2.14×10⁻³) = x → 2.92×10⁻⁷

That's the [OH⁻].  - log [OH⁻] = pOH

- log 2.92×10⁻⁷ = 6.53 → pOH

14 - pOH = pH → 14 - 6.53 = 7.47

4 0
3 years ago
According to the National Institute of Health, ventricular tachycardia is a fast, regular beating of the ventricles that may las
jarptica [38.1K]

Answer:

1 makes the most sense

Explanation:

There is no way blood pressure will be decreased especially if your ventricles are erratically contracting for a long period of time. So 3 and 4 are out. And you said number 2 is wrong so my finally answer is 1.

3 0
3 years ago
What are the names of the positive and negative electrodes of an electrolytic cell?
xz_007 [3.2K]

Answer:

the positive electrode is an anode, and the negative electrode is a cathode.

Explanation:

6 0
2 years ago
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