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ELEN [110]
3 years ago
13

How did uranium become present in Earth's upper crust? Choose one: A. It was delivered by comets that crashed into Earth's surfa

ce. B. It developed naturally in the upper crust. C. It rose upward as it was carried within magma. D. It does not exist in the upper crust. Uranium only exists in the mantle.
Chemistry
1 answer:
Luda [366]3 years ago
5 0

Answer:

<em>Option A. It was delivered by comets that crashed into Earth's surface.</em>

Explanation:        

<em><u>Uranium (U) is a chemical element with atomic number 92.</u></em>        

<em />

<em>For many years, a large number of scientists have been studying the abundance and origin of the isotopes of uranium in Earth</em>. <u>According to some theories, the Earth's uranium was produced in one or more supernovae</u> (an explosive brightening of a star), in wich, the main process consists in the rapid capture of neutrons by seed nuclei at great rates. <u>Another theory proposes that uranium is created during the merger of two neutron stars</u> (neutron stars are very dense), because, when such dense bodies come closer together the gravitational force cause them to merge, producing huge amounts of hevy metals like uranium.                  

<u><em>Many analyses have been made of the uranium in rocks of the Earth. These measurements shows that the abundance of uranium is bigger in the crust and upper mantle of the Earth</em></u>.    

So, knowing that Earth's uranium was produced through one of these processes, <u><em>the best answer is option A, the uranium was delivered by comets that crashed into Earth's surface.</em></u>    

Have a nice day!                            

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How many atoms are in 3 NaCl?
Assoli18 [71]

Explanation:

Sodium Chloride or NaCl is made up of two elements, sodium (or Na) and chlorine (or Cl). A molecule of sodium chloride, NaCl, consists of one atom each of sodium and chlorine. Hence, each molecule of NaCl has 2 atoms total.

5 0
3 years ago
HELP PLSSSSS!!
11Alexandr11 [23.1K]

Answer:

68133080.02 g

Explanation:

I believe that the question is to find the mass of air in the room and not the molar mass of air since the molar mass of air was already given in the question as 28.97 g/mol.

Now, if 1 mole of a gas occupies 22.4 L

x moles of air occupies 52,681,428.8 Liters

x = 1 * 52,681,428.8 /22.4

x = 2351849.5 moles of air

Now, number of moles = mass/ molar mass

but molar mass = 28.97 g/mol

2351849.5 = mass/28.97

mass = 2351849.5 * 28.97

mass = 68133080.02 g

7 0
3 years ago
The vapor pressure of a substance is measured over a range of temperatures. A plot of the natural log of the vapor pressure vers
Gala2k [10]

Answer:

28.7664 kJ /mol

Explanation:

The expression for Clausius-Clapeyron Equation is shown below as:

\ln P = \dfrac{-\Delta{H_{vap}}}{RT} + c

Where,

P is the vapor pressure

ΔHvap  is the Enthalpy of Vaporization

R is the gas constant (8.314×10⁻³ kJ /mol K)

c is the constant.

The graph of ln P and 1/T gives a slope of - ΔHvap/ R and intercept of c.

Given :

Slope = -3.46×10³ K

So,

- ΔHvap/ R = -3.46×10³ K

<u>ΔHvap = 3.46×10³ K × 8.314×10⁻³ kJ /mol K = 28.7664 kJ /mol</u>

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6 0
3 years ago
Complete each statement to identify the form of asexual reproduction.
Mrrafil [7]

Spore formation is a form of asexual reproduction used by mushrooms and molds.

During  budding, the offspring grows from the body of the parent.

Fragmentation is a form of asexual reproduction that must be followed by regeneration.

Explanation:

Asexual reproduction is the type of reproduction where the gamete formation and fusion have no relevance or existence. It functions on the process of somatic cell division via mitosis and the offsprings are identical to their parents.

The spore formation occurs in fungi through sporangia, bursting open to shed spores, forming into a new young ones. Budding occurs out as an outgrowth of the parent and attains maturity and separates. Fragmentation is the process where the parents fall apart into pieces and regeneration follows.

8 0
3 years ago
Read 2 more answers
When a diprotic acid is titrated with a strong base, and the Ka1 and Ka2 are significantly different, then the pH vs. volume plo
dezoksy [38]

Complete question is;

When a diprotic acid is titrated with a strong base, and the Ka1 and Ka2 are significantly different, then the pH vs. volume plot of the titration will have

a. a pH of 7 at the equivalence point.

b. two equivalence points below 7.

c. no equivalence point.

d. one equivalence point.

e. two distinct equivalence points

Answer:

Option E - Two Distinct Equivalence points

Explanation:

I've attached a sample diprotic acid titration curve.

In diprotic acids, the titration curves assists us to calculate the Ka1 and Ka2 of the acid. Thus, the pH at the half - first equivalence point in the titration will be equal to the pKa1 of the acid while the pH at the half - second equivalence point in a titration is equal to the pKa2 of the acid.

Thus, it is clear that there are two distinct equivalence points.

4 0
3 years ago
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