ASAP please 50 points!!!


Which of the following is a change in physical composition?

A. An iron nail rusting.

B. A purple substance forming when iodine is added to cornstarch.

C. Vinegar bubbling when baking soda is added.

D. A brick being ground up into fine dust.


Which of the following is a change in chemical composition?

A. A white precipitate forming as a result of the combination of two liquids.

B. An aluminum cube is rolled into a flat sheet.

C. Solid butter melting on the stove.

D. Liquid water freezing to form solid ice.


What kind of bond would you expect between H, S and O?

A. Metallic

B. None

C. Ionic

D. Covalent


Which of the following is not one of the three processes of the hydrologic cycle?

A. Evaporation

B. Collection

C. Condensation

D. Precipitation

your answer would be 2.0

Answer:

2.7 mol

Explanation:

we have the following reaction

[tex]3 H_2 + N_2\longrightarrow 2 NH_3[/tex]

Data

[tex]2.0 mol H_2\\4.0mol N_2\\mol NH_3= ?[/tex]

First we must calculate what the limit reagent is.

the limit reagent is consumed first, when it is consumed completely the reaction is finished

[tex]3molH_2\longrightarrow 1mol N_2\\4molH_2\longrightarrow x \\x=\frac{4molH_2.1molN_2}{3molH_2}=1.33mol N_2[/tex]

This means that in order to fully consume 4 moles of hydrogen, 1.3 moles of nitrogen are needed, since we have more than this amount of nitrogen (the nitrogen is in excess) is our excess reagent and hydrogen is our limit reagent. so much is it that determines how much product is formed

From the stoichiometric coefficients of the reaction we know that three moles of hydrogen are needed to produce two moles of ammonia

So how many moles of ammonia will be produced if we have 4 moles of hydrogen

To solve it we apply a simple rule of three

[tex]3mol H_2\longrightarrow 2 mol NH_3\\4molH_2\longrightarrow x \\x=\frac{2molNH_3.4molH_2}{3molH_2}=2.7 mol NH_3[/tex]

2.7 mol NH_3 are produced

✿ Clear Cutting a Forest is likely to cause the Loss of Soil by Erosion

Clear cutting forests primarily causes soil loss through erosion. Without the protection of trees, soil is easily washed away by rain and is no longer held in place by tree roots.

Clear cutting a forest is likely to cause the loss of soil primarily by erosion. When a forest is clear cut, it removes the trees that protect the soil from direct rain impact, causing the soil to be washed away easily. This is soil erosion. Furthermore, the tree roots that once secured the soil in place are no longer present, facilitating more rapid soil movement and loss. The process of soil erosion, like compaction, pollution, and overuse, can make the land unsuitable for vegetation growth. However, among the options given, clear cutting leads most directly to soil erosion.

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crystalize - cause to form crystals or assume crystalline form; "crystallize minerals" crystalise, crystallise, crystallize. natural philosophy, physics - the science of matter and energy and their interactions; "his favorite subject was physics"

I think it is oxidation number

Proton and an electron .

molar mass of methane CH4

= C + 4 H  

= 12.0 + 4 x 1.008

= 12.0 +  4.032

= 16.042g/mol

7.31 x 10^25 molecules x             1 mole  CH4      = 121.43 moles

                                       6.02 x 10^23 CH4 molecules

121.43 moles CH4 are present.

Answer : The number of moles of methane are, 121.39 moles

Explanation : Given,

Number of molecules of methane gas = [tex]7.31\times 10^{25}[/tex]

Now we have to calculate the number of moles of methane gas.

As, [tex]6.022\times 10^{23}[/tex] number of molecules of methane present in 1 mole of methane gas.

So, [tex]7.31\times 10^{25}[/tex] number of molecules of methane present in [tex]\frac{7.31\times 10^{25}}{6.022\times 10^{23}}\times 1mole=121.39[/tex] moles of methane gas.

Therefore, the number of moles of methane are, 121.39 moles

Answer:

They Both get benefited

Explanation:

Final answer:

In the relationship described, cattle egrets benefit by eating insects disturbed by grazing antelope, making it a commensal relationship where egrets benefit and antelope are typically unaffected. The correct answer to the question is A, with egrets gaining a food source from the activity of the antelope. So the correct option is A.

Explanation:

The relationship between cattle egrets and large grazing animals like rhinoceroses, elephants, antelope, and cows is a wonderful example of commensalism in nature. When large animals graze, they disturb insects in the grass, which the cattle egrets then feed on. This relationship is beneficial to the egrets as they gain a food source, but the large animals are neither harmed nor specifically benefitted by the presence of the egrets. However, sometimes there might be a slight advantage to the large animals if the egrets do remove pests like ticks or fleas, but this isn't the primary interaction.

Considering the relation between the cattle egrets and the antelope in the provided scenario, the most accurate answer would be:

This conclusion is based on the context of the question highlighting the egrets eating insects or small mammals that are disturbed by the grazing antelope.

Answers are in Word document.

Answer:

Explanation:

Bro im an excelletn as this but this was like two years ago

Hi There!

Obsidian - Igneous Rock

Marble - Metamorphic Rock

Conglomentary - Sedimentary Rock

Hope This Helps :)

Hey!

-------------------------------------------------

Answer:

Obsidian is an igneous rock.

Conglomentary is a sedimentary rock

Marble is an metamorphic rock.

-------------------------------------------------

Explanation:

Igneous Rock - which is formed through the process of solidification and cooling of magma.

Sedimentary Rock - which is formed through the process of particles being picked up from under bodies of water.

Metamorphic - Which is formed through the process of a rock going through physical or chemical changes.

-------------------------------------------------

Hope This Helped! Good Luck!

Answer: 1-2, 2-1, 3-3, 4-4

Explanation:

1. planet A is an inner planet as its distance from sun is 1.52 AU.

2. Planet B is an outer planet as its distance from sun is 19.22 AU.

3. planet A is Mars as it has only 2 moons.

4. planet B is Uranus because it has 27 moons.

Hence, 1-2, 2-1, 3-3, 4-4

I believe a and d are both compounds. Sorry I couldn't help you much.

Rainy weather has low pressure because it occurs when air mass warms causes the air layer to expand upward & outward causes to remove air from the colum, reducing air pressure.

The geometry and polarity of PF5 is trigonal bipyramidal, and it is a non-polar molecule due to its symmetrical shape causing the dipole moments to cancel out.

The geometry name for PF5 is trigonal bipyramidal. This is determined by the VSEPR model, which takes into account that PF5 has five bonding pairs of electrons and no lone pairs, giving it an AX5 designation. Since all electron groups are bonding pairs, no bond angle deviations from the ideal are expected.

Regarding polarity, PF5 is a non-polar molecule. This is because it has high symmetry with all the bonds being of identical polarity and oriented in a way that the dipole moments cancel out, resulting in a zero net dipole moment.

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1) Answer is: limiting reagent is hydrochloric acid.

Balanced chemical reaction: Mg + 2HCl → MgCl₂ + H₂.

m(Mg) = 25 g; mass of magnesium.

n(Mg) = m(Mg) ÷ M(Mg).

n(Mg) = 25 g ÷ 24.3 g/mol.

n(Mg) = 1.03 mol; amount of magnesium.

m(HCl) = 20 g; mass of hydrochloric acid.

M(HCl) = 36.46 g/mol; molar mass of hydrochloric acid.

n(HCl) = m(HCl) ÷ M(HCl).

n(HCl) = 20 g ÷ 36.46 g/mol.

n(HCl) = 0.55 mol; amount of hydrochloric acid.

2) From balanced chemical reaction: n(Mg) : n(HCl) = 1 : 2.

For 1.03 moles of magnesium 2.06 moles of hydrochloric acid is needed.

n(Mg) = n(HCl) ÷ 2.

n(Mg) = 0.55 mol ÷2.

n(Mg) = 0.225 mol.

m(Mg) = 0.225 mol · 24.3 g/mol.

m(Mg) = 6.66 g; mass of magnesium that reacts.

Δm(Mg) = 25 g - 6.66 g.

Δm(Mg) = 18.33 g; the excess reagent remains.

1) We know that there are 6.023 X 10^23 number of atoms or molecules or ions in one mole of a substance

In case of Magnesium it will have 6.023 X 10^23 number of atoms in one mole

The molar mass of Mg is 24 g/mol

so the mass of one mole of Mg will be 24g

Now moles of Mg in 35 grams = 35 / 24 = 1.458 moles

so number of atoms in 35g = moles X Na

[Where Na = Avagadro's number = 6.023 X 10^23]

number of atoms of Magnesium in 35g

                  = 1.458 X 6.023 X 10^23 = 8.78  X 10^23 atoms

2) The reaction is

Mg(s)  + 2HCl  ---> MgCl2(aq)  + H2(g)

So here one mole of Mg is reacting with two moles of HCl

The molar mass of Mg is 24 g/mol

so the mass of one mole of Mg will be 24g

The moles of Mg in 25 grams = 25 / 24 = 1.04 moles

similarly, Molar mass of HCl = 36.5 g / mol

So mass of one mole of HCl = 36.5 g

The moles of  HCl in 20g = 20 / 36.5  = 0.548 moles

Here for one mole of Mg we need two moles of HCl so for 1.04 moles of Mg we will need 2.08 moles of HCl

However we are provided with just 0.548 moles of HCl, hence HCl is the limiting reagent.

0.548 moles of HCl will react with 0.548 /2 moles of Mg

the moles of Mg reacted = 0.274 moles

Moles of excess Mg left = 1.04 - 0.274 = 0.766 moles

Mass of Mg left = moles left X molar mass = 0.766 X 24 = 18.38 g

Propane is a hydrocarbon and it will burn in presence of oxygen (it will undergo combustion) to give carbon dioxide and water (all in gas phase).

In presence of oxygen the carbon gets oxidized to carbon dioxide and hydrogen to water.

The general equation for a hydrocarbon undergoing combustion is

[tex]CxHy(g)  + (x+\frac{y}{4})O_{2}  ---> xCO_{2}(g)   +\frac{y}{2}H_{2}O(g)[/tex]

Here we are studying the combustion of propane so

x = 3

y = 8  

Propane has molecular formula of C3H8

Therefore the balanced equation will be

[tex]C3H8(g)  + (3+\frac{8}{4})O_{2}  ---> 3CO_{2}(g)   +\frac{8}{2}H_{2}O(g)[/tex]

Or

[tex]C3H8(g)  +   5O_{2} (g)  ---> 3CO_{2}(g) + 4H_{2}O(g)[/tex]

Answer:

B

Explanation:

its right

Protons= 88

Neutrons= 138.

The weight of an element is comprised of entirely protons and neutrons. To get the protons look at the atomic number on the periodic table (88) and those are your protons. To get the neutrons take the weight of the isotope that you have and subtract the protons, giving you 138.

Answer : The percent composition of Na, O and H elements are 57.47%, 40% and 2.52% respectively.

Solution : Given,

Molar mass of sodium = 22.99 g/mole

Molar mass of oxygen = 16 g/mole

Molar mass of hydrogen = 1.008 g/mole

First we have to calculate the molar mass of NaOH.

[tex]\text{ Molar mass of NaOH}=\text{ Mass of Na}+\text{ Mass of O}+\text{ Mass of H}[/tex]

[tex]\text{ Molar mass of NaOH}=22.99+16+1.008=39.998g/mole[/tex]

Now we have to calculate the percent composition of all the elements.

[tex]\%\text{ composition of Na}=\frac{\text{ Molar mass of Na}}{\text{ Molar mass of NaOH}}\times 100=\frac{22.99}{39.998}\times 100=57.47\%[/tex]

[tex]\%\text{ composition of O}=\frac{\text{ Molar mass of O}}{\text{ Molar mass of NaOH}}\times 100=\frac{16}{39.998}\times 100=40\%[/tex]

[tex]\%\text{ composition of H}=\frac{\text{ Molar mass of H}}{\text{ Molar mass of NaOH}}\times 100=\frac{1.008}{39.998}\times 100=2.52\%[/tex]

Therefore, the percent composition of Na, O and H elements are 57.47%, 40% and 2.52% respectively.

The percent compositions of Sodium, Oxygen, and Hydrogen in NaOH are 57.5%, 40%, and 2.5% respectively, based on their atomic masses and the molar mass of NaOH from the periodic table.

The percent composition of an element in a compound can be calculated using the atomic masses found on the periodic table and the molecular formula of the compound. The compound in question here is Sodium Hydroxide, or NaOH.

Firstly, let's find out the molar mass of NaOH. Sodium (Na) has an atomic weight of approximately 23 g/mol, Oxygen (O) is about 16 g/mol, and Hydrogen (H) is about 1 g/mol. Therefore, the molar mass of NaOH is 23 + 16 + 1 = 40 g/mol.

To find the percent composition, divide the atomic mass of each element by the total mass of the compound, then multiply by 100%. For Sodium: (23/40)*100% = 57.5%, for Oxygen: (16/40)*100% = 40%, and for Hydrogen: (1/40)*100% = 2.5%.

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In a neutralization reaction, equivalent volumes of solutions with equal normality will neutralize each other. Thus, 53 mL of 0.0050 N KOH will neutralize 53 mL of 0.0050 N H2SO4.

To answer the question 'How many milliliters of 0.0050 N KOH are required to neutralize 53 mL of 0.0050 N H2SO4 ?', we must understand the concept of neutralization in the context of acid-base reactions. Neutralization occurs when an acid reacts with a base to produce water and a salt, with no excess of hydrogen or hydroxide ions left in the solution.

In this case, the reaction is between KOH (Potassium Hydroxide, a base) and H2SO4 (Sulfuric Acid, an acid). As both solutions are of the same normality (0.0050 N), they will neutralize each other in equal volumes. Hence, 53 mL of 0.0050 N KOH are required to neutralize 53 mL of 0.0050 N H2SO4.

This concept ties into titration, a technique where a solution of known concentration (in this case, KOH) is used to determine the concentration of an unknown solution (H2SO4). It's important to note that this is a simplified example as it assumes 1:1 stoichiometry. For other reactions, it might be necessary to take into account the stoichiometric coefficients in the balanced chemical equation.

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Carbons starting from the left end:

Refer to the sketch attached.

The hybridization of a carbon atom depends on the number of electron domains that it has.

Each chemical bond counts as one single electron domain. This is the case for all chemical bonds: single, double, or triple. Each lone pair also counts as one electron domain. However, lone pairs are seldom seen on carbon atoms.

Each carbon atom has four valence electrons. It can form up to four chemical bonds. As a result, a carbon atom can have up to four electron domains. It has a minimum of two electron domains, with either two double bonds or one single bond and one triple bond.

Starting from the left end (H₂C=CH-) of the molecule:

Carbon atoms in a molecule can exhibit different kinds of hybridization, including sp³ and sp, leading to different molecular geometries such as tetrahedral and linear. For example, in acetylene, the carbon atoms have sp hybridization, forming a triple bond. In contrast, in a molecule like methane, the carbon atom undergoes sp³ hybridization, forming a tetrahedral structure.

In the context of the given molecule, we observe various types of hybridization in the carbon atoms. Specifically, carbon atoms 1 and 4 exhibit sp³ hybridization, indicated by their tetrahedral structure created by four single bonds. On the other hand, carbon atoms 2 and 3 are involved in a triple bond, leading to a linear geometry that signifies sp hybridization.

For instance, consider the molecule acetylene (H-C=C-H), where the two carbon atoms are attached by a triple bond due to sp hybridization. The sp hybrid orbitals of both carbon atoms form a σ bond between them and with the hydrogen atoms, while the remaining unhybridized p orbitals overlap side by side to form two π bonds.

Another form of hybridization can be observed in a molecule like CH4, where the carbon atom is surrounded by four hydrogen atoms, demonstrating sp³ hybridization. This tetrahedral structure gives methane its distinct shape. Overall, the type of hybridization a carbon atom undergoes is pivotal in determining the molecular geometry of the compound it forms.

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Answer:

The correct answer option is 1.6 atm.

Explanation:

We know that there is a sample gas which has a volume of 2.4 L with a pressure 1.2 atm and we are to find the pressure of the same gas sample if its volume is reduced to 1.8 L at a constant temperature.

We will apply the Boyle's law here which states that the "pressure of a given mass of an ideal gas is inversely proportional to its volume at a constant temperature".

[tex]P_1V_1=P_2V_2[/tex]

Substituting the values in the formula to get:

[tex]P_2=\frac{1.2*2.4}{1.8} \\\\P_2=1.6[/tex]

Therefore, the pressure of the same gas sample will be 1.6 atm if the volume is reduced to 1.8 L at a constant temperature.

The correct answer is option A, that is, HCl.  

An acid refers to an ion or molecule possessing the tendency of donating a hydrogen ion or a proton, or alternatively, exhibiting a tendency of producing a covalent bond with a pair of electrons. The aqueous Arrhenius acids exhibit characteristic features that offer a practical illustration of an acid.  

The acids can turn blue litmus paper red, can form aqueous solutions with a sour taste, and reacts with bases and some kind of metals to produce salts. One of the general aqueous acids is HCl (hydrochloric acid) that is found in the stomach and stimulates digestive enzymes.  

Among the options given, HCl (Hydrochloric acid) is considered to be an acid because it is listed under strong acids and releases hydrogen ions (H+) in aqueous solution, unlike the other options which are strong bases.

Looking at the list provided, we can identify HCl (Hydrochloric acid) as an acid. Bases are compounds that, in aqueous solution, release hydroxide ions (OH-), whereas acids are compounds that release hydrogen ions (H+) in aqueous solution. From the provided lists and examples in the reference information

HCl is listed under strong acids, clearly indicating it as an acidic compound

KOH (Potassium hydroxide), NaOH (Sodium hydroxide), and Ca(OH)2 (Calcium hydroxide) are mentioned as strong bases, hence they are not considered acids.

Therefore, the correct answer to which of the following is considered to be an acid is A) HCl.

Answer:

190 °C  

Step-by-step explanation:

The pressure is constant, so this looks like a case where we can use Charles’ Law:  

V₁/T₁ = V₂/T₂      Invert both sides of the equation.  

T₁/V₁ = T₂/V₂      Multiply each side by V₂

T₂ = T₁ × V₂/V₁

=====

V₁ = 3.75 L; T₁ = (37 + 273.15) K = 310.15 K  

V₂ = 5.6 L;   T₂ = ?  

=====

T₂ = 310.15 × 5.6/3.75

T₂ = 310.15 × 1.49

T₂ = 463 K

t₂ = 463 – 273.15

t₂ = 190 °C

speed of light=wavelength*frequency

3*10^8m/s=wavelength*1.20*10^13

wavelength=3*10^8/1.2*10^13

=10^-5/0.4=2.5*10^-5m

The excretory system words with the respiratory system to remove carbon dioxide.

It works with the respiratory system because it helps the lungs get rid of carbon dioxide and water vapors.

Hope this helps,

Davinia.

Scandium has 21 electrons, which are distributed according to its electronic configuration ([Ar] 3d¹4s²).

The number of electrons in an atom of scandium (Sc) is equal to its atomic number, which is 21. The electronic configuration of scandium is [Ar] 3d¹4s², denoting that there are 2 electrons in the 4s orbital and 1 electron in the 3d orbital, after the argon core.The number of electrons in an atom of scandium (Sc) is equal to its atomic number, which is 21.  Scandium is a transition metal and it is important to know that in its ionic form (Sc³+), it loses the 3 outer electrons and assumes an electronic structure similar to argon.

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X rays have the shortest wavelength among the given options, while ultraviolet radiation enables your body to make vitamin D.

The answer to the first question is D) X rays because X-rays have the shortest wavelength among the options given. X-rays have a wavelength range of 0.01 - 10 nanometers, which is shorter than the wavelengths of green light, radio waves, and infrared radiation.

The answer to the second question is A) ultraviolet radiation. When your skin is exposed to ultraviolet (UV) radiation from sunlight, it triggers a series of chemical reactions in your body that produce vitamin D.

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That would be when the baseball is rising. The energy from the throw is kinetic energy.

The position of elements on the periodic table is significant. The elements arranged in combination on the periodic table exhibit identical electronic configurations and thus identical reactivity and chemical properties. The vertical rows of elements are known as groups.  

Fluorine is a group 17 element. This group has a unique name, they are termed as halogens. Chlorine is also a halogen, they both exhibit seven valence electrons in their outer shell, and as such desires to take an additional electron for a stable octet to form the single charged anion.  

Oxygen is a group 16 element, exhibiting 6 valence electrons, and likes to prevail as the double charged anion. As a consequence, the chemical properties of fluorine more closely resemble with that of chlorine, and not with oxygen.  

Answer:

Mass of oxygen in glucose = 29.3g

Explanation:

Mass of glucose given is 55grams.

We are to find the mass of oxygen in this compound.

In the compound we have 6 atoms of oxygen.

Solution

To find the mass of oxygen in glucose, we calculate the formula mass of glucose. We now divide the formula mass of the oxygen atom with that of the glucose and multiply by the given mass to find the unkown mass.

Atomic mass of C = 12g

                           H = 1g

                           O = 16g

Formula mass of C₆H₁₂O₆ = {(12x6) + (1x12) + (16x6)} = 180

             Mass of O in glucose = [tex]\frac{6x16}{180}[/tex]  x 55

                                                  = [tex]\frac{96}{180}[/tex] x 55

                                                  = 0.53 x 55

            Mass of oxygen in glucose = 29.3g