Giselle is working with a chemical substance in a laboratory. She observes that when the chemical is heated, it gives off a gas. She assumes that the gas is oxygen but decides to test this assumption to verify it. Which type of scientific knowledge is Giselle’s assumption? A. fact B. hypothesis C. law D. observation E. theory

The equation is balanced. There are 4 aluminium atoms and 6 oxygen atoms on each side.

Answer:

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

[tex]n = \frac{N}{L} \\[/tex]

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question we have

[tex]n = \frac{4 \times {10}^{24} }{6.02 \times {10}^{23} } \\ = 6.644518...[/tex]

We have the final answer as

Hope this helps you

Answer:

An Exothermic Reaction , gives off more heat, and a little energy to its surroundings.

this can helps us figure out that the answer is , C, More heat is given off into its products.

Explanation:

Answer:

See Explanation

Explanation:

Positional Energy for electron as function of principle energy level (n)

=> Eₙ = -A/n²; A = 2.18x10⁻¹⁸J

Positional Energy for electron in n=2 => E₂ = -2.18x10⁻¹⁸/(2)² = -5.45x10⁻¹⁹J

Positional Energy for electron in n=3 => E₃ = -2.18x10⁻¹⁸/(3)² = -2.42x10⁻¹⁹J

ΔE(n=3→2) = -5.45x10⁻¹⁹J - (-2.42x10⁻¹⁹J) =   -3.03x10⁻¹⁹J

Answer:

False

Explanation:

Chemical and Physical changes happen uniquely, they cannot happen at the same time. When you crumble a piece of paper you don't change its chemical form you change its physical form. When a piece of metal rusts its chemical composition changes, leading me to believe it is false.

Good luck on the rest of your assignment/test!

Explanation:

Kendrick gave the bat potential Energy

Answer:

NaF, CaBr2, MgO

Explanation:

Hi! For this problem, you are going to want to look at the charges of the elements in order to write their formulas.

NaF: Na has a charge of +1 and F has a charge of -1. This means that they have a 1:1 ratio and the formula is written as such - NaF.

CaBr2: Ca has a charge of +2 and Br has a charge of -1. For this problem you want to make sure that their formal charge (the charge of the entire molecule) equals 0. This means that the negative charges need to equal the positive charges. Looking at this, you are going to need to Br ions with a charge of -1 to equal one Ca ion with a charge of +2 - CaBr2.

MgO: Mg has a charge of +2 and O has a charge of -2. This means that they have a 2:2 ratio which simplifies to a 1:1 ratio and the formula is written as such - MgO.

Hope this helps!

Answer:

B

Explanation:

The second one is not balanced correctly.

2 NaOH + 2HNO3 → 2NaNO3 + 2 H20

I didn't notice this before but it can be balanced without the twos.

 NaOH + HNO3 → NaNO3 +  H20

It was still wrong. It needed to have the twos removed, not 2 more added. Adding two more isn't wrong, but it should be balanced without 2s if at all possible.

Answer:

Explanation:

An atom is the smallest unit of an element that can take part in a chemical reaction. Atoms are made up of protons, neutrons and electrons. Atoms can exist as a monoatomic (such as in the case of Helium, Xenon and Neon) or as diatomic (such as in the case of oxygen and nitrogen). Atoms take part in a chemical reaction and there reactivity varies among themselves.

From the above, it can be deduced that atoms have protons, neutrons and electrons. The number of protons (which is positively charged) of an atom determines it's position on the periodic table because elements in the periodic table are arranged according to the number of protons (called atomic number). The electron(s) present in the outermost shell of each atom (called valence electrons) determines there chemical reactivity. What happens here is that, all atoms (except noble gases) want to achieve there duplet or octet configuration so as to become stable. This octet configuration means they want to have there outermost shell completely filled (with eight electrons or two electrons for duplet). They usually achieve this configuration by taking part in chemical reactions. Thus, when an atom has just one electron in it's outermost shell, it becomes easy to lose it to another atom by way of interacting with it in a chemical reaction. When it loses this single electron (valence electron) in it's outermost shell, it becomes stable with the inner completely filled shell (that would be the new outermost shell). Examples include Lithium, sodium and potassium. Sodium (with eleven electrons and three shells) would lose the single electron in it's outermost shell so as to have just two shells with the second shell completely filled with eight electrons. Thus, the more the valence electron to be lost to achieve the octet structure, the lesser the reactivity of the atom.

Also, an atom that has just one electron to complete it's own outermost shell and thus achieve it's octet structure is also highly reactive. This is also because it is easy for this atom to receive a single electron and become completely filled. Examples include chlorine, fluorine and iodine. Fluorine (with nine electrons and two shells) will easily accept one more electron so as to achieve it's octet structure with a completely filled outermost shell (of eight electrons). Thus, the lesser the electrons to be gained to achieve the octet configuration, the higher the chemical reactivity of such atoms. Noble gases have extremely low or no reactivity at all for this reason because it has a completely filled outermost shell (no losing or donating).

It should also be noted that metals (which are found on the left of the periodic table) exist as monoatomic while gases (which are found on the right), with the exception of noble gases, are mostly diatomic.

The reactivity of atoms of elements in the periodic table depends on their valency as well as their position in the periodic table.

The periodic table contains an arrangement of atoms in order of increasing atomic numbers. Elements in the periodic table are arranged in groups. Each group of elements have atoms that contain the same number of valence electrons.

Atoms of alkali and alkaline earth metals as well as atoms of halogens are highly reactive. This has something to do with the number of valence electrons they contain. The alkali and alkaline metals give out their electrons easily are high reactive while the halogens accept electrons easily are also highly reactive.

Alkali and alkaline earth metals have a few valence electrons so they give them out easily. Halogens have seven valence electrons hence they accept electrons easily. Reactivity of metals generally decreases from left to right in the periodic table while the reactivity of nonmetals increases from left to right. The elements of group 18 are placed in the last group because they are unreactive.

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Answer:  B. [tex]125\ cm^3[/tex].

The volume of the given object = [tex]125\ cm^3[/tex]

Explanation:

Given : Dimensions of an object : 5 cm x 5 cm  x 5 cm [ it is a cube with all equal sides]

Formula to find the volume of a cube = [tex](side)^3[/tex]

[tex]=5^3\ cm^3=125\ cm^3[/tex]

Hence, the volume of the given object = [tex]125\ cm^3[/tex]

Therefore , the correct option is B. [tex]125\ cm^3[/tex].

Answer:

D

Explanation:

Answer:d

Explanation:

Answer:

The liquid is likely to be a base e.g Sodium hydroxide solution or Ammonia solution

The liquid is likely to be a Base .

The terms acid and base describe chemical characteristics of many substances that we use daily. Acidic things taste sour. Basic or alkaline things taste soapy. Strong acids are corrosive and strong bases are caustic; both can cause severe skin damage that feels like a burn.  However, mild acids and bases are common and relatively harmless to us.

 2 H2O ⇌ 1 H3O+ + 1 OH-

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The answer is in the photo.

Answer:

Explanation: Fractional distillation

Answer:

The filter that water went through faster is Filter paper

Answer:

parts per billion

Explanation:

I took the quiz

Answer:

parts per billion

Explanation:

edge 2021

Answer:

5

Explanation:

An alkyl group is a functional group that contains only hydrogen and carbon atoms. It has the general formula: CnH2n+1.

Since n=2, plug it into the formula.

C2H2(2)+1

=

C₂H₅

Hope that helps.

The gas is confined in 3.0 L container ( rigid container) ⇒ the volume remains constant when the temperature is increased from from 27oC to 77oC and therefore V1=V2 .

Ideal gas law is valid only for ideal gas not for vanderwaal gas. Ideal gas is a hypothetical gas. Vanderwaal gas can behave as ideal gas at low pressure and high temperature. Therefore the final pressure is 1,750 mmHg.

Ideal gas equation is the mathematical expression that relates pressure volume and temperature.

Mathematically the relation between Pressure, volume and temperature can be given as

PV=nRT

where,

P = pressure of gas

V= volume of gas

n =number of moles of gas

T =temperature of gas

R = Gas constant = 0.0821 L.atm/K.mol

At constant volume, the above equation can be rearranged as

P₁/T₁ = P₂/T₂

Substituting all the given values in the above equation, we get

1500 ÷300= P₂÷350

P₂ =1,750 mmHg

Therefore the final pressure is 1,750 mmHg.

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Answer:

sorry if I get this wrong I think it is C

Explanation:

Answer:

Ksp = 2.4 * 10⁻⁵

Explanation:

The equation for the dissolution and dissociation of CaSO4 in water is given as: CaSO₄ ---> Ca²⁺ + SO₄²⁻

The expression for the Ksp of the dissociation equation above is:

Ksp = [Ca²⁺] [SO₄²⁻]

The molar ratio of the dissociated ions and the solute is 1 : 1, this means that every 1 mole of CaSO₄ that dissolves produces 1 mole of Ca²⁺ and SO₄²⁻ each

The molar solubility of a substance is the number of moles that dissolve per liter of solution.

molar solubility of CaSO₄ = number of moles /liter of solution

number of moles of CaSO₄ = mass/molar mass

molar mass of CaSO₄ = 136 g/mol

number of moles of CaSO₄ = 0.67/136 = 0.0049 moles

molar solubility of CaSO₄ = 0.0049 mol/ 1 L =  4.9 * 10⁻³ moles per liter

therefore, molar solubility of CaSO₄ = 4.9 * 10⁻³

Ksp = (4.9 * 10⁻³) (4.9 * 10⁻³)

Ksp = 2.4 * 10⁻⁵

Answer:

2.4 * 10^-5

Explanation:

Molar solubility of CaSO4  = 0 .67 g/L/136 g/mol = 4.9 * 10^-3 Mol/L

Given that;

CaSO4(s) -------> Ca^2+(aq) + SO4^2-(aq)

Hence, Ksp = [Ca^2+] [SO4^2-]

Where  [Ca^2+] =[SO4^2-]=s

Ksp = s^2

since s = 4.9 * 10^-3 Mol/L

Ksp = (4.9 * 10^-3 Mol/L)^2

Ksp = 2.4 * 10^-5

Answer:

transform battery

Explanation:

Answer: D. Transform Boundary

Explanation: I did the test.

Answer:

D

Explanation:

4 bars

Answer: 1.38

Explanation:

Gay-Lussac's Law: This law states that pressure is directly proportional to the temperature of the gas at constant volume and number of moles.

[tex]P\propto T[/tex]     (At constant volume and number of moles)

[tex]\frac{P_1}{T_1}=\frac{P_2}{T_2}[/tex]

where,

[tex]P_1[/tex] = initial pressure of gas  = 841 mm Hg

[tex]P_2[/tex] = final pressure of gas  = ?

[tex]T_1[/tex] = initial temperature of gas  =[tex]14.7^0C=(14.7+273)K=287.7K[/tex]  

[tex]T_2[/tex] = final temperature of gas = [tex]84.7^0C=(84.7+273)K=357.7K[/tex]  

[tex]\frac{841}{287.7}=\frac{P_2}{357.7}[/tex]

[tex]P_2=1045.6mm Hg=1.38atm[/tex]    ( 760 mm Hg = 1atm )

Thus the final pressure is 1.38