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matrenka [14]
2 years ago
13

If the radius of a coin is 14 cm, What is surface area?

Chemistry
1 answer:
antiseptic1488 [7]2 years ago
5 0
Let R=radius

Surface area of coin = π r²
where π can be typed in scientific calculator

Answer: π x 14 x 14 = 615.752 cm²
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What is the volume of 0.640 grams of Oz gas at Standard Temperature and Pressure (STP)?
Ilia_Sergeevich [38]

Answer: The volume of 0.640 grams of O_{2} gas at Standard Temperature and Pressure (STP) is 0.449 L.

Explanation:

Given: Mass of O_{2} gas = 0.640 g

Pressure = 1.0 atm

Temperature = 273 K

As number of moles is the mass of substance divided by its molar mass.

So, moles of O_{2} (molar mass = 32.0 g/mol) is as follows.

No. of moles = \frac{mass}{molar mass}\\= \frac{0.640 g}{32.0 g/mol}\\= 0.02 mol

Now, ideal gas equation is used to calculate the volume as follows.

PV = nRT

where,

P = pressure

V = volume

n = no. of moles

R = gas constant = 0.0821 L atm/mol K

T = temperature

Substitute the values into above formula as follows.

PV = nRT\\1.0 atm \times V = 0.02 mol \times 0.0821 L atm/mol K \times 273 K\\V = 0.449 L

Thus, we can conclude that the volume of 0.640 grams of O_{2} gas at Standard Temperature and Pressure (STP) is 0.449 L.

6 0
3 years ago
A certain atom has 11 electrons 8 neutrons and a charge of -1. What is it’s atomic mass
Arlecino [84]

Answer:

20 amu

Explanation:

An atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.

All these three subatomic particles construct an atom. A neutral atom have equal number of proton and electron. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other. For example if neutral atom has 6 protons than it must have 6 electrons. The sum of neutrons and protons is the mass number of an atom while the number of protons are number of electrons is the atomic number of an atom.

Atomic mass = Number of protons + number of neutrons

Atomic number = Number of electrons or number of protons.

In given question it is stated that atom has 11 electrons and -1  charge it means this atom has 12 electrons in neutral state.

Thus it has 12 protons because number of electrons and protons are always equal.

Atomic mass of given atom:

Atomic mass = Number of protons + number of neutrons

Atomic mass = 12 + 8 = 20 amu

7 0
3 years ago
How many valence electrons does lithium (Li) have available for bonding?
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Lithium has 1 valence electron available for bonding. So its A.
6 0
3 years ago
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What is the percent composition of sodium oxide?
4vir4ik [10]

Sodium : 74.186%

Oxygen : 25.814%

7 0
3 years ago
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Help me with my work please thanks?!
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Answer:

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