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3 years ago

Approximately, how many national parks are there in the United States? a. 25 b. 50 c. 120 d. 474

Chemistry

2 answers:

Len [333]3 years ago

7 0

B, I would believe. There are 58, but B is the closest we can get.

Art [367]3 years ago

3 0

The correct answer is - b. 50.

The United States have approximately 50 national parks, or to be more specific, there's 58 of them on the territory of this vast North American country. One of the best known and most visited parks that are a global tourist attraction are the Yellowstone National Park, The Grand Canyon National Park, and the Yosemite National Park. There are also many national parks in the United States that we can easily say are underrated and are in the shadow of these three, but at least that is good for the nature because the less people are visiting them, the less damage will be done to them.

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Find the weight of HNO_3 present in 20ml, 0.30 N

yanalaym [24]

Answer:

mass of HNO₃ = 0.378 g

Explanation:

Normality = Molarity * number of equivalents

Molarity = Normality/number of equivalents

normality of HNO₃ = 0.30 N, Volume = 20 mL

HNO₃ ionizes in the following way:

HNO₃(aq) ----> H⁺ + NO₃⁻

Therefore, number of equivalents for HNO₃ is 1

molarity of HNO₃ = 0.30/1 =0.30 mol/dm³

Using the formula, molarity = number of moles/volume in liters

number of moles = molarity * volume

Number of moles of HNO₃ = 0.30 mol/dm³ * 20ml * 1 dm³ /1000 mL

number of moles = 0.006 moles

From the formula, mass = number of moles * molar mass

molar mass of HNO₃ = 63.0 g/mol

mass = 0.006 * 63

mass of HNO₃ = 0.378 g

6 0

3 years ago

How is an oscilloscope used to tune a musical instrument?

sp2606 [1]

It uses the voltages and sound freq. in the air to measure the wave lengthths

4 0

3 years ago

A group 2 metal carbonate has a mass of 84 g/mol. Identify the group 2 metal X using its chemical formula.

zepelin [54]

Answer:

Magnesium

0.003mole

Explanation:

The problem here entails we find the metal in the carbonate.

For group 2 member, let the metal = X;

The carbonate is XCO₃;

If we sum the atomic mass of the elements in the metal carbonate, we should arrive at 84g/mol

Atomic mass of C = 12g/mol

O = 16g/mol

Atomic mass of X + 12 + 3(16) = 84

Atomic mass of X = 84 - 60 = 24g/mol

The element with atomic mass of 24g is Magnesium

Number of moles in 0.3g of CaCO₃:

Molar mass of CaCO₃ = 40 + 12 + 3(16) = 100g/mol

Number of moles = $\frac{mass}{molar mass}$

Number of moles = $\frac{0.3}{100}$ = 0.003mole

7 0

3 years ago

O tetraclorometano é um solvente muito utilizado na indústria de transformaç?o de produtos orgânicos ele é produzido pela reaç?o

Vlada [557]

Answer:

ΔHr = -103,4 kcal/mol

Explanation:

Using:

AH° (kcal/mol)

Metano (CH)

-17,9

Cloro (CI)

tetraclorometano (CCI)

- 33,3

Acido cloridrico (HCI)

-22

It is possible to obtain the ΔH of a reaction from ΔH's of formation for each compound, thus:

ΔHr = (ΔH products - ΔH reactants)

For the reaction:

CH₄(g) + Cl₂(g) → CCl₄(g) + HCl(g)

The balanced reaction is:

CH₄(g) + 4Cl₂(g) → CCl₄(g) + 4HCl(g)

The ΔH's of formation for these compounds are:

ΔH CH₄(g): -17,9 kcal/mol

ΔH Cl₂(g): 0 kcal/mol

ΔH CCl₄(g): -33,3 kcal/mol

ΔH HCl(g): -22 kcal/mol

The ΔHr is:

-33,3 kcal/mol × 1 mol + -22 kcal/mol× 4 mol - (-17,9 kcal/mol × 1 mol + 0kcal/mol × 4mol)

ΔHr = -103,4 kcal/mol

I hope it helps!

3 0

3 years ago

When does the given chemical system reach dynamic equilibrium?

AVprozaik [17]

Once it becomes balanced.

7 0

3 years ago