the mass number of an element whose atoms contain 18 protons, 22 neutrons and 18 electrons

Answer:

20g

Explanation:

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High conductivity of metals is caused by electrons that are free to move through the lattice.

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Answer:

Explanation:

Chemists categorize chemical changes into three main classes: inorganic chemical changes, organic chemical changes, and biochemical changes.

Burning of paper and log of wood.

Digestion of food.

Boiling an egg.

Chemical battery usage.

Electroplating a metal.

Baking a cake.

Milk going sour.

Various metabolic reactions that take place in the cells.

a.

The atomic radius of iridium is 1.355 Å

For a face-centered cubic unit cell, with edge length, a and atomic radius r,

we have a² + a² = (4r)²

2a² = 16r²

r² = a²/8

r = a/√8

Since a = 3.833 Å,

Substituting this into the equation, we have

r = a/√8

r = 3.833 Å/√8

r = 3.833 Å/2.828

r = 1.355 Å

So, the atomic radius of iridium is 1.355 Å

b.

The density of iridium metal is 22.67 g/cm³

To find the density of the iridium metal, we need to find the mass of atoms per unit cell.

So, for the face centered cubic iridium atom, there are 6 faces per unit cell × 1/2 atoms per face + 4 corners per unit cell × 1/4 atoms per corner = 3 atoms + 1 atom = 4 atoms per unit cell.

So, the mass of the atoms in the unit cell is m = number of atoms/cell × number of moles/atom × molar mass of Iridium

= 4 atoms/cell × 1 mol/6.022 × 10²³ atoms × 192.22 g/mol

= 768.88/6.022 × 10²³ g/cell

= 127.68 × 10⁻²³ g/cell

= 1.2768 × 10⁻²¹ g/cell

Next, we need to find the volume of the unit cell which is V = a³

= (3.833 Å)³

= (3.833 × 10⁻¹⁰ m)³

= 56.314 × 10⁻³⁰ m

= 5.6314 × 10⁻²⁹ m

So, the density of iridium = mass of unit cell/volume of unit cell

= m/V

= 1.2768 × 10⁻²¹ g/cell ÷ 5.6314 × 10⁻²⁹ m

= 0.2267 × 10⁸ g/m³

= 0.2267 × 10⁸ g/m³ × 10⁻⁶ m³/cm³

= 0.2267 × 10² g/cm³

= 22.67 g/cm³

So, the density of iridium metal is 22.67 g/cm³

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Answer:

I think you may have chosen the wrong subject for your question, besides where is the context to this?

Explanation:

Electrons are closer to the nucleus are in filled orbitals and are called core electrons. More energy which in nucleus called nuclear strOng energy to remove electron thars why its also a way harder too..

1 mole of oxygen.

Answer:

solution given:

[tex]2Na+O_2=Na_2O_2\\2mole\:\: 1mole \:\: 1mole[/tex]

according to the above reaction,1 mole of oxygen is required to react with 2 moles of sodium to form sodium peroxide.

Explanation:

Answer:

The answer is designing an experiment

Explanation:

Since we already have a hypothesis, we need to test the hypothesis and this is done by designing an experiment that will do this test.

Answer:

increase

Explanation:

Let's suppose we have a sample of air in a closed container. We heat the container and we want to predict what would happen to the pressure.

According to Gay-Lussac's law, the pressure of a gas is directly proportional to its absolute temperature.

Thus, if we increased the temperature of the air by heating it, its pressure would increase.

If a sample of air in a closed container was heated, the total pressure of the air would increase.

Answer:

hydrogen and helium is the answer.

Answer:

its called Toxoplasmosis.

Explanation:

Cats become infected by Toxoplasma gondii by ingesting the cysts of this parasite. Most often, this occurs when cats eat mice or rats infected with the parasite. However, they can also ingest it during grooming after coming in contact with infected soil or feces.

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The line spectra of an atom offers conclusive evidence that electron energies are quantized.

Neils Bohr showed that electrons in an atom can absorb or emit energy when they move from one energy level to another. This principle is the basis upon which the spectra of atoms is built.

The true statements about the atomic spectra is;

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Answer:

2.4×1024 atoms.

Explanation:

Please mark me as brainliest

Answer:

If a compound is made from a metal and a non-metal, its bonding will be ionic. If a compound is made from two non-metals, its bonding will be covalent.

Answer:

it because of cold weather

Answer:

the answers are given in the photo

Answer:

Word equation: Potassium chlorate → Potassium chloride + Oxygen

Chemical equation: KClO₃ → KCl + O₂

Explanation:

This is decomposition reaction so there will only be one reactant, which is potassium chlorate.

The chemical equation will be:

KClO₃ → KCl + O₂

The balanced equation would be:

2KClO₃ → 2KCl + 3O₂

The word equation will be:

Potassium chlorate → Potassium chloride + Oxygen

Answer:

170 dm³ (2 significant figures)

Explanation:

CH₄ + 2O₂ → CO₂ + 2H₂O

We need to find how much 'volume' of O₂ is required to burn 56 g of CH₄.

Let's take the ratios of the two gases only.

CH₄ : 2O₂ (in terms of moles the ratio is 1:2)

56g : x dm³

Mr of CH₄ : Volume of oxygen at rtp

Find the Mr of CH₄.

Mr of CH₄ = 12 + (1 × 4) = 16

We know that 1 mole of any gas occupies 24 dm³ at room temperature and pressure (rtp). We have to find the volume of oxygen, there are 2 moles of oxygen, so 2 moles of gas will occupy:

2 × 24 = 48 dm³

56g : x dm³

  16 : 48 dm³

16x = 56 × 48

16x = 2688

x = [tex]\frac{2688}{16}[/tex]

x = 168 dm³

∴ the minimum volume of oxygen gas, at room temperature and pressure required to completely burn 56g of methane gas is 170 dm³

[tex]\huge \bf༆ Answer ༄[/tex]

The trends showing increase in ionization energy on the periodic table ~

[ due to increase in effective nuclear charge ]

[ Due to decrease in number of shells ]

Ionization energy increases across a period from left to right in the periodic  table.

Ionization energy is the energy needed for the complete removal of valence electrons in its ground state from an isolated atom in its gaseous phase at a specified temperature to form an ion.

Ionization energy shows periodicity in that it shows a regular variation across a period and down a group in the periodic table.

Ionization energy increases across a period from left to right in the periodic  table.

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Answer:

nothing

Explanation:

Answer:

1. Ethane has a higher boiling point

2. Heptyne has a higher boiling point

3. Octane has a higher boiling point

Explanation:

1. Ethane has stronger intermolecular attractions (van der Waal's forces) than ethene and so has the higher boiling point.

2. The longer (and the straighter) the chain, the greater the opportunity for intermolecular interactions, and thus the greater the boiling point. You should look up these boilig points! n-Pentane has a normal boiling point of approx. 36 ∘C ; n-heptane boils at 98 ∘C .

3. Octane has a high boiling point, because its molecule contains 8 Carbon atoms, and with increasing molecular weight of hydrocarbon its boiling temperature increases.

Answer:

2) To find the atoms from the moles, you just multiply Avogadro's number (6.02 x 10^23) by the moles.

So 3.35 x (6.02 x 10^23) = 2.0167 x 10^24 atoms are in 3.35 moles of aluminum

3) If the question is asking under standard temperature and pressure, we know that if we divide the volume by the molar volume of a gas (which is 22.7 in standard temperature and pressure), we can get the moles.  

So 101.25L / 22.7 = 4.46 mol

4) We know that to find the moles, it is the mass divided by the molar mass. If we rearrange the equation to solve for mass, we have to multiply the moles by the molar mass to get there.

Nitrogen's (N) molar mass on the periodic table is 14g/mol, but since Nitrogen is a diatomic element, it would be N2 by itself. So multiply 14 by 2, which will give you 28g/mol. N2's molar mass is 28g/mol.

Now you multiply 13.7 moles by 28g/mol, which will give you 383.6g

Just did a few edits here, 4.46 for question 3 is in moles not L

Taking into account the definition of avogadro's number,

2. 3.35 moles of aluminum contains 2.018ײ⁴ atoms.

3. 4.52 moles of CO₂ gas are in a 101.25 L container filled with CO₂ gas.

4. 13.7 moles of N₂ contain 383.6 grams.  

Avogadro's Number is called the number of particles that make up a substance (usually atoms or molecules) and that can be found in the amount of one mole of said substance. Its value is 6.023×10²³ particles per mole. Avogadro's number applies to any substance.

Then you can apply the following rule of three: if 1 mole of aluminum contains 6.023×10²³ atoms, then 3.35 moles of aluminum contains how many atoms?

amount of atoms of aluminum= (6.023×10²³ atoms × 3.35 moles)÷ 1 mole

amount of atoms of aluminum=2.018ײ⁴ atoms

Finally, 3.35 moles of aluminum contains 2.018ײ⁴ atoms.

The STP conditions refer to the standard temperature and pressure. Pressure values at 1 atmosphere and temperature at 0 ° C are used and are reference values for gases. And in these conditions 1 mole of any gas occupies an approximate volume of 22.4 liters.

Then, you can apply the following rule of three: If by definition of the STP conditions 1 mole of CO₂ occupies a volume of 22.4 L, how many moles does 101.25 L occupy?

[tex]amount of moles of CO_{2} =\frac{101.25 Lx1 mole of CO_{2} }{22.4 L}[/tex]

amount of moles of CO₂= 4.52 moles

4.52 moles of CO₂ gas are in a 101.25 L container filled with CO₂ gas.

The molar mass of substance is a property defined as its mass per unit quantity of substance, in other words, molar mass is the amount of mass that a substance contains in one mole.

In this case, the molar mass of N₂ is 28 g/mole. So, you can apply the following rule of three:  If 1 mole of N₂ contains 28 grams, 13.7 moles of N₂ contain how much mass?

[tex]mass=\frac{13.7 moles x28 grams}{1 mole}[/tex]

mass= 383.6 grams

13.7 moles of N₂ contain 383.6 grams.

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Archaea (Archaeon ): Single-celled microorganisms without nuclei and with membranes different from all other organisms. Once thought to be bacteria.

Unicellular organism

-A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Unicellular organisms fall into two general categories: prokaryotic organisms and eukaryotic organisms.

A 1.00 mole of Sulfuric acid (H₂SO₄) contains the largest number of atoms (7 atoms/molecule). Option B is correct.

To determine which of the given compounds contains the largest number of atoms in 1.00 mole, we need to consider the number of atoms in each compound.

1.00 mole of NH₃ contains:

1 mole of N atoms (1 atom/molecule)

3 moles of H atoms (3 atoms/molecule)

Total atoms = 1 + 3 = 4 atoms/molecule

1.00 mole of H₂SO₄ contains:

2 moles of H atoms (2 atoms/molecule)

1 mole of S atoms (1 atom/molecule)

4 moles of O atoms (4 atoms/molecule)

Total atoms = 2 + 1 + 4 = 7 atoms/molecule

1.00 mole of HBr contains:

1 mole of H atoms (1 atom/molecule)

1 mole of Br atoms (1 atom/molecule)

Total atoms = 1 + 1 = 2 atoms/molecule

Therefore, 1.00 mole of H₂SO₄, contains the largest number of atoms.

Hence, B. is the correct option.

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