I have no idea what to do with this? Its a Niels Bohr and electons practice sheet. Need help asap

Coffee thermos- Maintains heat in the thermos through insulation

Kitchen Appliances- Applicances such as refrigerators keep items cool, while toasters and pots are used to heat items up

Lunchbox- Many lunchboxes are insulated with materials that enables the box to keep cool.

Answer:

There are [tex]1.207\times 10^{24} atoms[/tex] in 80.2 grams of calcium.

Explanation:

Atomic mass of calcium = 40 g/mol

Mass of calcium given = 80.2 g

Moles of calcium = [tex]\frac{80.2 g}{40 g/mol}=2.005 mol[/tex]

1 mol = [tex]N_A=6.022\times 10^{23} [/tex] atoms/ molecules, ions

Number of atoms of calcium in 2.005 moles of calcium:

[tex]2.005 \times 6.022\times 10^{23}=1.207\times 10^{24} atoms[/tex]

There are [tex]1.207\times 10^{24} atoms[/tex] in 80.2 grams of calcium.

The number of atoms in 80.2grams of calcium is 1.207 × 10²⁴ atoms.

The number of atoms of an element can be calculated by multiplying the number of moles of the substance by Avogadro's number as follows:

no of atoms = no of moles × Avogadro's number

According to this question, 80.2grams of calcium are given. Calcium has a molar mass of 40.0g/mol. The number of moles can be calculated as follows:

no of moles = 80.2g ÷ 40g/mol = 2.005mol

No of atoms = 2.005mol × 6.02 × 10²³

no of atoms = 1.207 × 10²⁴ atoms

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Chemical change: a change that occurs when one substance combines with another substance to make a new substance

Physical change: a change to any physical property of a substance

The chemical property of hydrogen gas is that it burns in the air.  

• The lightest element is hydrogen, it can explode at concentrations ranging from 4 to 75 percent by volume in the existence of a flame, sunlight, or a spark.  

• One of the prime chemical properties of hydrogen gas is that it is highly flammable and can burn in air at a very broad array of concentrations that is between 4 to 75 percent by volume.  

• Some of the physical properties of hydrogen gas are that it is colorless, odorless, nonmetallic, non-toxic, exhibits a density of 0.09 grams per liter, and has a boiling point of -252.87 degree C or 20 K at standard pressure.  

Thus, of the mentioned statements, option 2 is correct, that is, the chemical property of hydrogen gas is that it burns in the air.  

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Only an apple will float when placed in water.

An object will float in water if its density is less than that of water (1.0 g/mL).

An object will sink in water if its density is greater than that of water.

Thus, solid objects made of gold, iron, or rubber will all sink in water.

The answer is 40.5.

Standard form is in answered or not in a different form.

So, you must solve this.

4.05 * 10 = 40.5

Have a great day :) Let me know if you need help with anything else!

The question asked about converting a number in scientific notation to standard form. The number 4.05 x 10 is converted into its standard form by moving the decimal point of 4.05 one place to the right, which gives us 40.5.

The number provided is in a format known as scientific notation. To convert it to its standard form, we just need to follow a few steps. The number provided is 4.05 x 10. Converting this to standard form involves multiplying the number outside the 'x' (i.e., 4.05) by 10. However, as there's no specified power of 10 provided (like 10^2, 10^3 etc.), we assume it to be 10^1. So, we simply move the decimal point in 4.05 one place to the right because it's 10^1. Thus, the standard form of 4.05 x 10 is 40.5.

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I am pretty sure the answer is C, but I am not certain.

The correct answer is A.) 3d

Answer is: A) it would increase .

Boyle's Law (the pressure-volume law): volume of a given amount of gas held at constant temperature varies inversely with the applied pressure when the temperature and mass are constant.  

p₁V₁ = p₂V₂ (the product of the initial volume and pressure is equal to the product of the volume and pressure after a change).

For example:

p₁ = 1.2 atm; starting pressure.

V₁ = 2.0 L., starting volume.

V₂ = 1.0 L; final volume, smaller than starting volume.

p₂ = ?; final pressure.

1.2 atm · 2 L = p₂ · 1 L.  

p₂ = 1.2 atm · 2 L / 1 L.  

p₂ = 2.4 atm.

When volume goes up, pressure goes down.  

When volume goes down, pressure goes up.  

13. Bilateral. If it were to split up, it would create an equal two sides.

14. Since the butterfly has the same symmetry as the sea slug, it would seem as though it matches well with it. As the question states that most organisms relate more because of symmetry, this would be a definite answer. Even though they are not the same organism family.

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An Environmental Impact Study is used to provide a sufficient level of detail to demonstrate that a proposed development will have no negative impacts on the natural features or ecological functions of the subject and surrounding (“adjacent”) lands. Hope this helps!!!

A. I, III, and IV only.

Answer:

A. I, III, and IV only

Explanation:

The cycling of water in and out of the atmosphere is an important determinant of weather and climate. Changes in humidity and average rainfall usually depend on this factor.

Uneven heating of the earth by the sun also creates unique patterns of changes in weather and climatic conditions around the world.

Global patterns of atmospheric movement affect parameters such as wind speed etc.

Mass defect and binding energy are related as

ΔE = Δmc^2

Where

ΔE = binding energy

Δm = mass defect

c = speed of light

given

mass defect = 3.09x 10-27 kg

We know that speed of light = 3 X 10^8 m /s

ΔE = 3.09x 10-27 kg  (3 X 10^8 m /s)^2 = 2.781 X 10^-10 J / Kg

.

.

Answer:

A

Explanation:

2.78 × 10-10 J Is the answer

Reactivity is a chemical property, energy transferring between products and reactants is true of a chemical reaction, melting a substance and metal denting are physical changes, while digesting a sandwich is a chemical change.

The chemical property of a substance from the given options is reactivity. A chemical property is related to how a substance interacts with other substances, and reactivity is an example of this.

For a chemical reaction, it's accurate to say that energy is transferred between products and reactants. During a chemical reaction, energy can either be absorbed or released, indicating a transfer of energy.

An example of a physical change from your list would be melting a substance. Physical changes involve a change in the physical properties of a substance, like its state of matter, but the substance itself doesn't change.

A chemical change involves a substance changing into a new substance with different properties. In this case, digesting a sandwich is a chemical change because it causes the food to break down into different substances.

Finally, from your list, an example of a physical change would again be metal denting. A physical change alters a substance without changing its composition, like denting a metal object does.

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Topaz scratches quartz

Answer:

The correct answer is :'Topaz scratches quartz'.

Explanation:

Mohs scale is a qualitative scale to analyse and characterize scratch resistance of minerals.Harder mineral will easily scratch softer mineral.

Lower value on the scale indicates that mineral can be easily scratched by the another mineral with higher scale value. In other words calcite with scale value of 3 can easily scratch gypsum  and talc with scale value of 2 and 1 respectively.

So, from the given options the correct test is that topaz scratches quartz.

Answer:

A) Matter cannot be subdivided.

Explanation:

Hope this comes to your aid.

Matter are anything that is made up of atoms. The quantity of matter can be observed only on the basis of mass and volume calculation. Therefore, the incorrect statement is matter cannot be subdivided.

Matter is a substance that has some mass and can occupy some volume. The matter is mainly used in science. Matter can be solid, liquid or gas.

Matter is anything that is made up of atoms. Anything around us that can be physically seen and touched are matter. Ice, water and water vapors are example of matter.

So as we saw that matter has some mass so mass can be measured in gram only. Mass can also be represented as number of molecules. We also saw that matter occupy some volume and that volume is measured only in liter. Degree of Celsius is used to measure temperature which has nothing to do with matter.

Therefore, the incorrect statement is matter cannot be subdivided.

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It takes 33.4 s for the concentration of A to fall to one-fourth of its original value.

A half-life is the time it takes for the concentration to fall to half its original value.

Assume the initial concentration is 1.00 mol/L. Then,

[tex]\text{1.00 mol/L }\stackrel{\text{1st half-life }}{\longrightarrow}\text{ 0.50 mol/L } \stackrel{\text{ 2nd half-life }}{\longrightarrow}\text{0.25 mol/L}\\[/tex]

The concentration drops to one-fourth of its initial value in two half-lives.

∴ Time = 2 × 16.7 s = 33.4 s

Answer:

The answer is D.) It is a base because it increases the concentration of hydroxide ions.

Explanation:

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Answer:

It is a base because it increases the concentration of hydroxide ions.

Explanation:

The first step is canceling out the like term, in this case it is the atoms and mole specification.  I use e instead of multiplying times 10 to a power, it is mostly used in higher sciences but I think it is easier and it is in most calculators.  So your equations is 7.43e22 Mg multiplied by (1/6.02e23) multiplied by (24.30) Mg.  So all together it is 7.43e22 (1/6.02e23) (24.30).  Then just multiply across, it is easier to break it up.  7.43e22 times (1/6.02e23)= .1234219269.  Take that and multiply it by 24.30.  So that looks like (0.1234219269)x(24.3)= 2.999152824.  So if it would be 2.9992 grams of Mg.

Answer:

35.8 u

Explanation:

The atomic mass of Cl is the weighted average of the atomic masses of its isotopes.

We multiply the atomic mass of each isotope by a number representing its relative importance (i.e., its percent abundance).

Atomic mass of Cl-35 = 17p + 18n = 17 × 1.007 u + 18 × 1.009 u

= 17.119 u + 18.162 u = 35.28 u

Atomic mass of Cl-37 = 17p + 20n = 17 × 1.007 u + 20 × 1.009 u

= 17.119 u + 20.180 u = 37.30 u

Set up a table for easy calculation.

0.755 × 35.28 u =  26.64  u

0.245 × 37.30 u =    9.138 u

              TOTAL = 35.8     u

Note: The actual atomic mass of Cl is 35.45 u.

The calculated value above is incorrect because

(a) the given isotopic percentages are incorrect and

(b) the protons and neutrons have less mass when they are in the nucleus than when they are free. Thus, the calculated masses of Cl-35 and Cl-37 are too high.

The average atomic mass of chlorine can be calculated as a weighted average of its two isotopes' masses, with weights reflecting their proportions. Isotopes are variations of an element with different numbers of neutrons, and understanding them helps us calculate average atomic masses. Similar calculations apply for other elements with multiple isotopes, such as boron.

The subject of this question is the average atomic mass of the element chlorine (Cl), given the proportions of its two isotopes: chlorine-35 and chlorine-37, with the respective proportions of 75.5% and 24.5%. The calculation is similar to finding a weighted average. This involves multiplying each individual isotope mass by its percentage (expressed as a decimal), and then adding the products together: (35amu*0.755) + (37amu*0.245).

Isotopes are variations of an element that have the same number of protons, but different numbers of neutrons. This concept is important in understanding the calculation of an element's average atomic mass. The atomic mass listed on the periodic table for each element is a weighted average of its isotopes' masses, with the weights being the natural abundance of each isotope. This is why elements, even those with atomic masses in square brackets due to their unstable nature, have precise average atomic masses.

For example, a similar element, boron, has two isotopes as well: 19.9% of all boron atoms are ¹0B with a mass of 10.0129 amu, and the remaining 80.1% are ¹¹B with a mass of 11.0093 amu. The average atomic mass for boron is then also a weighted average, calculated in a similar way to chlorine.

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The reaction is a synthesis…

[tex]4Al + 3O_2 \longrightarrow 2Al_2O_3\\[/tex]

… because two substances are combining to make one other substance.

[tex]4\stackrel{\hbox{0}}{\hbox{Al}} + 3\stackrel{\hbox{0}}{\hbox{O}}_2 \longrightarrow 2\stackrel{\hbox{+3}}{\hbox{Al}}_2\stackrel{\hbox{-2}}{\hbox{O}}_3\\[/tex]

It is also a reduction-oxidation reaction because the oxidation number of Al increases from 0 to +3 and the oxidation number of O decreases from 0 to -2.

usually its rubber please give me the brainliest!

It is yet unknown compound having highest melting point of all compounds.

It is made up of right amounts of  hafnium, nitrogen, and carbon would have a melting point of more than 4400 K (7460°F).

That's about two-thirds the temperature at the surface of the sun and 200 K higher than the highest melting point ever recorded experimentally.

Answer:

Metals are malleable.

Explanation:

The metals are the substances possessing an abundant amount of electrons. They are placed majorly on the left side of the periodic table. The metals are considered as the good conductors of electricity and heat, they are lustrous in appearance, and usually have a high melting point. However, the main property, which distinguishes it from other substances is that they are malleable and ductile, that is, they can be transformed into wires and thin sheets.

The correct answer is option B.

An ephemeral stream is one that flows only after rainfall.

Ephemeral streams only exist for a short period of time. They are often found in the desert landscape. Desert climate is arid with sparse to no vegetation. Without plants in the soil, rain water does not get absorbed, and so after rainfall excess water flow as ephemeral streams.

B. An ephemeral stream is one that flows only after rainfall

Final answer:

Transition metals in groups 1B-8B on the periodic table display similar properties such as high melting and boiling points, good electrical and heat conductivity, and the ability to form colored compounds.

Explanation:

The elements in groups 1B-8B on the periodic table, also known as transition metals, display similar properties. These elements have partially filled d orbitals in their electron configurations, which give them their unique characteristics. Some common properties of transition metals include high melting and boiling points, good conductors of electricity and heat, ability to form colored compounds, and variable oxidation states.

Therefore, the required properties are high melting and boiling points, good electrical and heat conductivity, and the ability to form colored compounds.

Final answer:

Ecology, paleontology, and botany are all branches of biology, which is the area of science they pertain to.

Explanation:

If someone told you they had a career in either ecology, paleontology, or botany, they would be working in the area of biology. These are all branches of biological science that deal with different aspects of living organisms and their environments. Ecology involves the study of how organisms interact with each other and their environment, paleontology uses fossils to understand the history of life on Earth, and botany focuses on the study of plants. Biology, as a natural science, encompasses a variety of fields that all aim to understand the various facets of life and living organisms.

It is the same as an elements number of protons.

The correct answer is option 4 and 5.

The electron domain geometry for an ammonia molecule, NH₃ has tetrahedral electron domain geometry. In NH₃ there are three bond pair electrons and one lone pair electron. Therefore, NH₃ has four electron pairs which are distributed in a tetrahedral shape.

The molecular geometry for an ammonia molecule, NH₃ is trigonal-pyramidal molecular geometry. Ammonia has one lone pair of electron and three bond pairs of electrons thus the resulting molecular geometry is trigonal-pyramidal.  

For an ammonia molecule, the electron domain geometry is tetrahedral, and the molecular geometry is trigonal pyramidal. Therefore, the fourth and fifth option is correct.

The electron domain geometry describes the arrangement of electron domains around the central atom, where an electron domain can be a bond or a lone pair of electrons.

Molecular geometry refers to the arrangement of atoms in a molecule, considering both the bonding and nonbonding electron pairs.

In ammonia, the three hydrogen atoms are bonded to the central nitrogen atom, and the nitrogen atom has one lone pair of electrons.

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Answer:  + 4 m/s

Working Out:

V = Δ x  ÷  Δ t ;where V =  velocity, Δ x = displacement, Δ t = change in time

V = Δ x  ÷  Δ t

V = (12 m east) ÷ 3.0 s

V = 4 m/s to the east  OR V = + 4 m/s

∴ The velocity of the wave is + 4 m/s

Answer:

4 m/s

Explanation: TOOK THE TEST