What is the correct Lewis structure for a molecule of ammonia, NH3?
:-N-A
H-N-H
Н
H-NH

Answer:

B. False

Explanation:

All the atoms of an element are not entirely the same no matter where they are found.

The phenomenon of isotopy brings a different perspective to the identity of an element.

Answer:

90 Minutes

Explanation:

Original concentration = 120 mg

Half life = 30 minutes

Minimum level = 15 mg

Basically, we are to calculate the time it would take to drop from 120 mg to 15 mg.

The half life of a substance is the time it takes for the original concentration of a substance to drop to half it's starting concentration.

First Half life:

Starting concentration = 120mg

Concentration after half life = 120 / 2 = 60 mg

Second Half life;

Starting concentration = 60 mg

Concentration after half life = 60 / 2 = 30 mg

Third Half life;

Starting concentration = 30 mg

Concentration after half life = 30 / 2 = 15 mg

We have reached the minimum 15 mg level. This means it took three half lives to get there.

Total time taken = No of Half lives * Half life duration = 3 * 30 mins = 90 Minutes

Answer:

4 mol

Explanation:

Given data:

Number of atoms of He = 2.4 × 10²⁴ atoms

Number of moles of He = ?

Solution:

Avogadro number:

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

1 mole = 6.022 × 10²³ atoms

2.4 × 10²⁴ atoms × 1mol / 6.022 × 10²³ atoms

0.398× 10¹ mol

3.98 mol ≅ 4 mol

Answer: Fossil fuels are rich in carbon, and burning them releases carbon into the atmosphere.

Explanation:

The amount of carbon in the form of carbon dioxide in the atmosphere is about 0.03% by volume. This value is kept fairly constant by a natural process known as the CARBON CYCLE. This involves carbon dioxide being continually removed from the atmosphere by plants in photosynthesis, rain water as weak acids while in order to maintain this balance, carbon dioxide is at the same time returned to the atmosphere by:

--> burning of carbon containing substances (fossil fuel)

--> respiration of plants and animals and

--> Decomposition of organic substances.

Therefore the role of fossil fuels which are rich in carbon content releases carbon into the atmosphere when burnt.

Answer:

13.33 g/dm³

Explanation:

Concentration (g/dm³)= mass(g) ÷ volume (dm³)

Now you need to convert 150 cm³ to dm³

1000cm³ = 1 dm³

thus, 150 cm3= 150 ÷ 1000

= 15dm³

and you already have mass in grams

so concentration  = 2 ÷ 0.15

= 13.33 g/dm³ and there you go.. solved ;)

Answer:

NH₄NO₃

Explanation:

In salt naming, the cation is named first, then you must put the name of the anion. In the same way when you are writting the formula. Also, the global charge of a salt is always 0.

Thus, we must write each ion and its charge:

Ammonium: NH₄⁺

Nitrate: NO₃⁻

As both ions have the same charge, the formula is:

The cation first and then the anion.

Answer:

The energy transported by a wave is directly proportional to the square of the amplitude. So whatever change occurs in the amplitude, the square of that effect impacts the energy. This means that a doubling of the amplitude results in a quadrupling of the energy.

Answer:

The Rock does not contain carbonate in it.

Explanation:

Limestone(CaCO_3) when reacts with a acid produces carbon dioxide, which comes out as bubbles in the solution. It means the 4th rock does not have carbonate in it. Carbonate minerals are unstable in contact with hydrochloric acid. When acid begins to effervesce (fizz) on a specimen. These bubbles confirms the presence of carbonate in mineral.

Answer:

no,exept y and z are similar

Explanation:

litterly what it says '-'

Answer:

C

Explanation:

so the way that waves are created normally is by slight breezes the stronger the breeze the bigger the wave so if strong winds are produced  it will result in large waves

Hope this helped you and check out my YT my most popular video at Ryetube ExTrEmE

Answer:

When heat is added to a substance, the molecules and atoms vibrate faster. As atoms vibrate faster, the space between atoms increases. The motion and spacing of the particles determines the state of matter of the substance. ... Solids, liquids and gases all expand when heat is added.\

so hope that helps and sooooo

Answer:

When heat is added to a substance, the molecules and atoms vibrate faster. As atoms vibrate faster, the space between atoms increases. The motion and spacing of the particles determines the state of matter of the substance. ... Solids, liquids and gases all expand when heat is added.

1. 4

2. 4

3. 2

4. 2

Given

Reaction

2H₂+O₂⇒2H₂O

Required

Number of atoms

Solution

In compounds, the number of atoms of the constituent components in the form of elements is usually indicated by a subscript after the element symbol, while the number in front of the compound which is the coefficient indicates the number of molecules of the compound.

In chemical reactions, the reactants are on the left and the products on the right

1. Number of Hydrogen in reactants

2 molecules x 2 atoms = 4 atoms

2. Number of Hydrogen in products

2 molecules x 2 atoms = 4 atoms

3. Number of Oxygen in reactants

1 molecules x 2 atoms = 2 atoms

3. Number of Oxygen in products

2 molecules x 1 atoms = 2 atoms

The reaction is said to be balanced because the number of atoms of the element is the same between the reactants and products

Answer:

0.967mole

Explanation:

Given parameters:

Volume of NH₄Cl  = 21.67L

Unknown:

Number of moles  = ?

Solution:

We assume that the volume was taken at standard temperature and pressure,

 Then;

  Number of moles  = [tex]\frac{volume }{22.4L}[/tex]  

 Number of moles  = [tex]\frac{21.67}{22.4}[/tex]   = 0.967mole

Answer:

Dr. Tierno tested the pillows for signs of microorganisms. He took samples from the pillow, then he grew the microorganisms in a petri dish.

Explanation:

This is the answer on edmentum

Answer:

B: It is extremely reactive

Explanation:

Potassium metal is also soft and white with a silvery lustre, has a low melting point, and is a good conductor of heat and electricity.

Answer: Properties, occurrence, and uses. Potassium metal is soft and white with a silvery lustre, has a low melting point, and is a good conductor of heat and electricity. Potassium imparts a lavender colour to a flame, and its vapour is green.

Explanation: hope it helps

Answer:

All collisions between particles are perfectly elastic

Explanation:

found it somehwere else

The statement, that describes postulate of the kinetic-molecular theory is "all collisions between particles are perfectly elastic."

A collision would be any process where two or even more objects exert forces on one another quickly.

The kinetic-molecular theory explains matter states and is based on the assumption that matter is made up of small particles that are always in motion. It is a simple, historically significant classical model of the thermodynamic behavior of gases that established several fundamental thermodynamic ideas.

Because the molecules are so small, the kinetic theory of gases assumes that the collision between them is fully elastic. Because the molecules are so small, their energy and momenta are conserved during collisions. As a result, regardless of collisions, the temperature remains constant.

Hence the correct option is all collisions between particles are perfectly elastic.

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Answer:

(B) It is tetrahedral because there are four bonded pairs around carbon

Explanation:

CCl4 means four chloride ions bonded covalently with single carbon.

its coordination figure is:

CF =  1/2(Vallence of central atom + electrons donated from substituents - charge)

CF = 1/2(4 + 4.1 - 0)

CF = 4

Bond electrons = 4

Lone pair electrons = 0

Hence, CCl4 is tetrahedral

Explanation:

If you look back at the formula ( SO2 ), you can see that there is one sulfur and two oxygens present. Therefore, the molar mass of sulfur dioxide is [1 × 32.1 + 2 × 16.0] = 64.1 g/mol.

Answer:

Buffalo and Watertown.

Explanation:

This is correct as the Interior lowlands are located ib the US. These are correct as the others are in the US but aren't located anywhere near the Interior Lowlands.

Answer: Different parts of the sun rotate at different rates.

Explanation:

The statement that best describes the motion of the sun is that different parts of the sun rotate at different rates.

First and foremost, we should note that the rotation of the sun is on its axis and also the sun isn't a solid. Due to this, its motion will be that there'll be rotation of different part of it at different rates. Assuming the sun was solid, then all of its parts will move together.

Answer:

Different parts of the sun rotate at different rates.

Explanation: pic proof

Answer:

How many moles H2O in 1 grams? The answer is 0.055508435061792.

We assume you are converting between moles H2O and gram.

You can view more details on each measurement unit:

molecular weight of H2O or grams

This compound is also known as Water or Dihydrogen Monoxide.

The SI base unit for amount of substance is the mole.

1 mole is equal to 1 moles H2O, or 18.01528 grams.

Explanation:

The mass of 4.0 moles of water is 72 grams.

Explanation:

[tex]Moles=\frac{\text{mass of substance}}{\text{molar mass of substance}}[/tex]

Given:

The 4.0 moles of water

To find:

Mass of moles of water

Solution:

The moles of water = 4.0 moles

The mass of water = M

The molar mass of water = 18.01528 g/mol

[tex]4.0=\frac{m}{ 18.01528 g/mol}\\m=4.0\times 18.01528 g/mol\\=72.06112 g\approx 72 g[/tex]

The mass of 4.0 moles of water is 72 grams.

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Answer: (4) C-14 to 6-12

Explanation:

Carbon dating is used to estimate the age of wooden trees which use carbon dioxide. Carbon has three naturally occurring isotopes.C-12 and C-13 are stable but C-14 is radioactive. C-14 decays to nitrogen-14 and has a half-life of 5,730 years.

Wooden trees naturally incorporate both the C-12 and C-14 during their lifetimes. When wooden trees die, it stops consuming more of radioactive carbon while the C-14 which is already present in them continues to decay back into nitrogen. With the help of C-12 to C-14 ratio, we can estimate the age of wooden objects.

The age of ancient wooden objects is  investigated using the C-14 to C-12.

Carbon dating provides an effective way to determine the age of a sample. The idea here is that all living organisms give out C-14 while they are alive and the amount of the isotope in a living sample is known.

The age of a sample is obtained by comparing the level of the C-14 isotope present in it to the amount present in a living tissue. Hence, the age of ancient wooden objects is  investigated using the C-14 to C-12.

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Answer:

b

Explanation:

Beryllium is under Group 2, and group 2 are usually known as alkaline earth metals.

Answer:

Its electrical to thermal energy

Explanation: