pleaseee PLEASEEE PLEASEEE I NEED HELPPP!!

can someone do these for me I will give brainliest

The emission spectrum of an atom consists of limited lines that are unique to a given element.

According to the Bohr model of the atom, energy is absorbed or emitted when an atom moves from one energy level to another. Since energy is quantized, the spectrum of atoms often consists of single lines.

Hence, the true statement about atomic spectrum is that; "the light that an element emits is made up of a limited number of narrow lines that produce a unique pattern or atomic emissions spectrum for that element."

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Answer:

Mass of 0.5 moles of CO2 is 22 gm.

Explanation:

1 mole of CO2 = 44 gm

0.5 mole of CO2 = 0.5 × 44 = 22 gm

Answer:

answer is b

Explanation:

I think it is b. I don't know what land lenses are but focusing light on the can would heat it up more.

Answer:

Frequency

Explanation:

It’s kinda self-explanatory but bascially speed=wavelength times frequency

Answer:

Frequency is Speed divided by Wavelength

Step-by-step explanation:

Don't think there needs to be an explanation for the formula, unless you want the conceptual understanding

Explanation:

Different isotopes of an element have different numbers of mass number

Answer:

The number of valence electrons goes up by one each time you move

Answer:

the Aluminium Al have +3 charges and idion have I) have - 2 charges

Answer:

false

Explanation:

because it's just a physical change, the matter won't be changed.

Hope this might help you! I don't know if this is going to be right on everything, but it's a anwser

In a physical change, the makeup of matter is changed. This statement is false.

A physical change occurs when a substance experiences a change in its physical characteristics. A physical alteration may usually be reversed. No new material is produced with such a transformation.

As the substance's composition changes, a chemical reaction takes place. A chemical change happens when bonds are broken and new ones are created.

Physical change is a sort of change when the substance's chemical makeup does not change. Often, this type of alteration entails a change in the substance's size, form, and condition.

Thus, In a physical change, the makeup of matter is not changed because it's a physical change.

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The bonding activity that occurs between phosphorus and chlorine is Covalent Bonding

Covalent bonding is an interaction between two atomic elements that share electrons between themselves.

In Phosphorus Pentachlorine PCl₅, covalent bonding occurs between Phosphorus and Chlorine.

This is because, Phosphorus is the central atom that is attached to 5 different chlorine atoms, each chlorine atom needs one electron each to complete its octet rule and since phosphorus has five valence electrons in its outermost shell, it shares it with each of the chlorine atoms.

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Answer:

Covalent Bonding

Answer:

5.24 x 10^23

Explanation:

Avogadro's constant is 6.02 x 10^23

1 mol = 6.02 x 10^23

0.87 mol = 6.02 x 10^23 x 0.87 = 5.24 x 10^23 (2.d.p)

Answer:

No

Explanation:

Despite mercury being a metal, it is a liquid at room temperature. It cannot be an electrolyte. This is because most of the liquids that can conduct electricity or acids bases and salts whereas mercury is a metal.

The paths that planets follow around the sun are called as orbit, and they are shaped like an ellipse.

The orbits of the planets around the sun are elliptical. Kepler, an astronomer, provided a clear definition of these orbits. The three rules he created are referred to as Kepler's laws of planetary motion. It says that every planet does an orbit around the sun.

The plane of Earth's orbit around the sun serves as the definition of the ecliptic. The primary planets of our solar system, their moons, some asteroids, and their orbits all roughly follow this plane.

An orbit is a curved path taken by an object, such as a planet's path around a star, a natural satellite's path around a planet, or a man-made satellite's path around a planet, moon, or asteroid.

Thus, the paths that planets follow around the sun are called as orbit.

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The enthalpy of reaction for the decomposition of calcium carbonate is 177.4  KJ/mole .

We know that the enthalpy of reaction can be obtained from the enthalpy of formation of the reactants and that of the products using the formula;

ΔHrxn = ΔHf (products) - ΔHf (reactants)

The heat of formation of the species are as follows;

ΔHf (CaCO3(s)) = −1206.9 KJ/mol

ΔHf (CaO(s)) =  - 636 KJ/mole

ΔHf (CO2(g)) = -393.5  KJ/mole

ΔHrxn = [( -393.5  KJ/mole ) + ( - 636 KJ/mole)] - [ −1206.9 KJ/mol]

ΔHrxn = 177.4  KJ/mole

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Answer:

First one is 656.3 and second is endothermic.

Explanation:

Edge Thermochemical Equations assignment

Answer:

14.54 g Fe2O3

Explanation:

The first step would be to balance the equation but since it's already balanced we don't have to worry about that.

Through the balanced equation, you can find the stoichiometry of the reaction, that is:

4 moles of Fe, react with 3 moles of O2, to produce 2 moles of Fe2O3

Chemistry (accurately stoichiometry) is all about ratios and proportions. The balanced equations gives you the standard ratio by which moles are produced.

So the next step (shown in the paper), is to convert the grams that are giving you in Moles, and you do this by dividing the number of grams given by the molar mass of the substance. The molar mass is the number of grams by which you can find exactly 6.022x10²³ molecules (one mole) of one specific substance.

15.4 g of Fe= 0.28 mol Fe

3.6 g of O2= 0.11 mol O2

Now that you have the quantity of moles, what you need to do is to look for the limitant reactant.

In a balanced equation, the number of moles in the reactants are the rules and they're gonna react completely with each other. If you want x quatity of reactants to react completely, then you will have to respect the proportion to the ratio given in the balanced equation.

But you will rarely follow the proportion so there will usually be a reactant that's gonna be limiting the reaction and one that is in excess. And how do you find this? Well, the easiest way to do it is:

Since the limitant reactant is gonna be limiting the reaction, all the stoichiometric procedures should be calculated through it, and in this case, the limitant reactant is O2.

But then how to establish the stoichiometric rule to find the number of Iron oxide (III) that's being produced?

Look back to the stoichiometry of the reaction:

To produce 2 moles of Fe2O3, you need 3 moles of O2.

But you have 0.11 mol O2.

Then establish a factor of conversion (shown in the picture)

The result is 0.07 mol of Fe2O3, but you need the answer in grams so you find the molar mass of Fe2O3 and then multiply it by the number of moles (0.07)

The answer is 14.54 g of Fe2O3

CHEMISTRY IS ALL ABOUT PROPORTIONS :D

Answer:

Mole is a number that connects mass of a substance with its number of particles. 2500 g of O2 = 1/32 x 2500 = 78.125 moles

Explanation:

have a great day

Answer:

Mn(NO3)3 Molar mass = (54.93) + (3 x 14) + (9 x 16) = 240.93g/mol

Total number of Oxygen atoms in formula = 9

Total mass of oxygen atoms theoretically in the formula = 9x16 = 144g/mol

Oxygen's percentage composition:

(144/240.93) x 100 = 59.7% of the compound is oxygen

We are given that–

[tex]\qquad[/tex]________________________

As we know –

[tex]\qquad[/tex][tex] \pink{\bf\longrightarrow {Mass = Volume \times Density } }[/tex]

[tex]\qquad[/tex][tex] \bf\longrightarrow Mass_{(Propane)} = 389 \times 19.3 [/tex]

[tex]\qquad[/tex][tex] \bf\longrightarrow Mass_{(Propane)} = 7507.7 \: g[/tex]

[tex]\qquad[/tex]______________________

Mass of a substance is the amount of the constituting particles per unit volume. The mass of the [tex]\bold { 389\ cm^3}[/tex] of propane is 7.507 kg.

Mass of a substance is the amount of the constituting particles per unit volume. It is measured in kilograms (kg).

The formula for mass,

M =  v x d

Where,

M - mass

v - volume = [tex]\bold { 389\ cm^3}[/tex]

d - density = 19.3 g/cm

Put the values in the formula,

M =  [tex]\bold { 389\ cm^3}[/tex]  x   19.3 g/cm

M = 7507.7 g

M  = 7.507 kg

Therefore, the mass of the [tex]\bold { 389\ cm^3}[/tex] of propane is 7.507 kg.

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We can extract 3×3 power 3 from glucose molecules

Answer:

it is a nice question....my mind tells me that the first is it use me as a good vibes and can use to anything the second i will do my best too absorbe it.

Explanation:

Hope this help...

HC= Hydrocarbon

CH=benzene

Explanation:

HC is Hydrocarbon, how? -- Hydrocarbon, a category of substances consisting only of hydrogen and carbon.

CH is benzene, how? -- benzene is represented by the empirical formula CH, which indicates that a typical sample of the compound contains one atom of carbon (C) to one atom of hydrogen (H).

----(Is this what you meant???)

Answer:

2-

Explanation:

Oxygen always act with an oxidation number of 2- unless we're talking of peroxide such as H2O2, where oxygen acts with an oxidation number of 1-

The diagram in image (4) in the image attached represents a sample of oxygen gas at stp.

Oxygen is a diatomic molecule, a diatomic molecule is a molecule that consists of only two atoms of the same element. In this case, the oxygen molecule consists of two oxygen atoms.

If we look at the diagram in the image attached very well, we will discover that the image in diagram (4) shows a molecule composed of two atoms of the same element and this fits exactly into the description of the oxygen molecule.

Learn more about diatomic molecules:

Particle diagram 4 represents the particles of oxygen at standard temperature and pressure.

A model of molecular (or diatomic) oxygen, which is made up of two oxygen atoms attached to each other through a covalent bond.

Dioxygen, also known as oxygen, is a naturally occurring molecule made up of two oxygen atoms that attach to each other with a strong covalent bond to form oxygen (dioxygen). Oxygen is sp3-hybridized, i.e. it has 4 sp3 hybrids. One of these hybrid orbitals overlaps with the s orbitals of hydrogen to create the O-h sigma bonds.

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The diagram in question is attached below.

The reaction, Fe2O3 + 3CO------> 2Fe + 3CO2 is an oxidation-reduction reaction.

An oxidation-reduction reaction is a reaction in which there is a change in oxidation number from left to right in the reaction. This is because, a specie is oxidized and another specie is reduced.

In the reaction;  Fe2O3 + 3CO------> 2Fe + 3CO2, we can see that the oxidation number of iron decreased from +3 on the left hand side to zero on the right hand side. The oxidation number of carbon was increased from + 2 to +4.

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Answer:

A

Explanation:

EDGE2022

Answer:  Antimony: Antimony is used to create firework glitter effects. Barium: Barium is used to create green colors in fireworks,

Explanation:

Answer:

Explanation:Antimony: Antimony is used to create firework glitter effects. Barium: Barium is used to create green colors in fireworks, 

Answer:

0.178M

Explanation:

The question can immediately be understood as comparing two states.

- The initial state M1 , V1.

- The Final state M2 , V2.

M - Molarity.

V - Volume (in mili liters/ml/ in this case).

The formula is stated as:

M1 * V1 = M2 * V2

Given- Required

M1 = 0.125M V1 = 265ml M2 = ?

V2 = 186ml

rearranged formula - M2 = M1 * V1 / V2 = 0.125M * 265ml / 186ml

= 0.178091397 M ~ ~ 0.178M.