I need help on this question plzzz

Answer:

Surely you must have a Periodic Table beside you....?

a=38

Explanation:

You gots Z=18, the atomic number, where Z is the number of nuclear protons. The number of protons defines the element....and thus we got calcium....

....and with 20 neutrons we got the 38Ca isotope....the which is rather short-lived...

Answer:

its keplers first law

Explanation:

answer from gauth math

The property altered during a chemical change that is not altered during a physical change is composition of the matter.

A physical change is one in which no new substance is formed and it is easily reversible.

A chemical change is one that is not easily reversible and no new substance is formed. It may be accompanied by absorption or evolution of heat.

The composition of a substance changes during a chemical change  because bonds between atoms break and new bonds are formed. This does not occur during a physical change.

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The chemical formula for peracetic acid is C2H4O3. This means that there are 2 atoms of carbon, 4 atoms of hydrogen, and 3 atoms of oxygen in a single molecule.

I think that the answer is C2H4O3.

Answer:

D. All pure substances are molecules.

The correct statement about pure substances is; "All molecules are pure substances."

A pure substance contains exactly the same type of atoms. In a molecule, there can only be a particular combination of atoms.

For instance, a molecule of HCl can only contain chlorine and hydrogen atoms.

This means that every molecules are also pure substances.

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Answer:

none of the above answers

Answer:

[tex]\boxed {\boxed {\sf 928.8 \ grams}}[/tex]

Explanation:

Density is the mass per unit volume of a substance. The following formula is used for calculating density.

[tex]\rho= \frac{m}{v}[/tex]

We know the density of aluminum is 2.70 grams per milliliter. The mass is unknown, but we know the piece of aluminum has a volume of 344 milliliters.

Substitute these values into the formula.

[tex]2.70 \ g/mL = \frac {m}{344 \ mL}[/tex]

We are solving for the mass, so we must isolate the variable m. It is being divided by 344 milliliters. The inverse operation of division is multiplication. Multiply both sides of the equation by 344 mL.

[tex]344 \ mL *2.70 \ g/mL = \frac {m}{344 \ mL} * 344 \ mL[/tex]

[tex]344 \ mL *2.70 \ g/mL =m[/tex]

The units of milliliters cancel.

[tex]344 *2.70 \ g=m[/tex]

[tex]928.8 \ g =m[/tex]

The mass of the piece of aluminum is 928.8 grams.

Answer:

Explanation:

The number of cactus plants would increase.

Answer:

16

Explanation:

1) in the given equation CH₄+2O₂⇒ 2H₂O+CO₂;

M(CH₄)=12+4=16 (g/mol); M(O₂)=32 (g/mol);

2) if m(O₂)=125 gr., then ν(O₂)=m(O₂)/M(O₂)=125/32≈3.90625 (moles);

3) if in the given equation 'ν' of O₂ is 2, then the 'ν' of CH₄ is 1;

4) m(CH₄)=ν(CH₄)*M(CH₄)=1*16=16 (gr.).

Answer:

i. 1 : 2

ii. NaOH is the limiting reagent

iii. 292.5g

iv. 59.69%

Explanation:

I have the detailed and self-explanatory workings. will snap and post later. Battery percent at 15%, flashlight not working.

1. The ratio of CuSO₄ to NaOH is 1 : 2

2. The limiting reactant is NaOH.

3. The mass of Cu(OH)₂ that will precipitate out is 292.5 g.

4. The percentage yield of Cu(OH)₂ is 59.7%

1. Determination of the ratio of CuSO₄ to NaOH.

CuSO₄ + 2NaOH —> Cu(OH)₂ + Na₂SO₄

From the balanced equation above, we can see that the ratio of CuSO₄ to NaOH is 1 : 2

2. Determination of the limiting reactant.

CuSO₄ + 2NaOH —> Cu(OH)₂ + Na₂SO₄

Molar mass of CuSO₄ = 63.5 + 32 + (16×4) = 159.5 g/mol

Mass of CuSO₄ from the balanced equation = 1 × 159.5 = 159.5 g

Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol

Mass of NaOH from the balanced equation = 2 × 40 = 80 g

From the balanced equation above,

159.5 g of CuSO₄ reacted with 80 g of NaOH.

Therefore,

638.44 g of CuSO₄ will react with = (638.44 × 80) / 159.5 = 320.22 g of NaOH.

From the calculations made above, we can see that a higher mass (i.e 320.22 g) of NaOH than what was given (i.e 240 g) is needed to react completely with 638.44 g of CuSO₄.

Therefore, NaOH is the limiting reactant.

3. Determination of the mass of Cu(OH)₂ that will precipitate out.

CuSO₄ + 2NaOH —> Cu(OH)₂ + Na₂SO₄

Molar mass of Cu(OH)₂ = 63.5 + 2(16 + 1) = 97.5 g/mol

Mass of Cu(OH)₂ from the balanced equation = 1 × 97.5 = 97.5 g

From the balanced equation above,

80 g of NaOH reacted to produce 97.5 g of Cu(OH)₂.

Therefore,

240 g of NaOH will react to produce = (240 × 97.5) / 80 = 292.5 g of Cu(OH)₂

Thus, 292.5 g of Cu(OH)₂ precipitated out of the reaction.

4. Determination of the percentage yield.

Percentage yield = (Actual /Theoretical) × 100

Percentage yield of Cu(OH)₂ = (174.6 / 292.5) × 100

Percentage yield of Cu(OH)₂ = 59.7%

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Answer:

[tex]\boxed{\boxed {\sf 5930.0 \ mol \ CH_4}}[/tex]

Explanation:

We are asked to find how many moles of methane (CH₄)  a cow produces in a year. We must convert molecules of methane to moles of methane. We will do this using Avogadro's Number or 6.022 × 10²³. This is the number of particles (atoms, molecules, formula units, etc.) in 1 mole of a substance.

In this case, the particles are molecules of methane. There are 6.022 × 10²³ molecules of methane in 1 mole.

We will convert molecules to moles using dimensional analysis. Set up a ratio using Avogadro's Number.

[tex]\frac {6.022 \times 10^{23} \ molecules \ CH_4}{ 1 \ mol \ CH_4}[/tex]

We are converting 3.571 × 10²⁷ molecules of methane to moles, so we multiply the ratio by this value.

[tex]3.571 \times 10^ {27} \ molecules \ CH_4 *\frac {6.022 \times 10^{23} \ molecules \ CH_4}{ 1 \ mol \ CH_4}[/tex]

Flip the ratio. It is still the same value, but the units of molecules of methane cancel.

[tex]3.571 \times 10^ {27} \ molecules \ CH_4 *\frac { 1 \ mol \ CH_4}{6.022 \times 10^{23} \ molecules \ CH_4}[/tex]

[tex]3.571 \times 10^ {27} *\frac { 1 \ mol \ CH_4}{6.022 \times 10^{23} }[/tex]

[tex]\frac {3.571 \times 10^ {27}}{6.022 \times 10^{23} } \ mol \ CH_4[/tex]

[tex]5929.923613 \ mol \ CH_4[/tex]

The original measurement of molecules of methane( 3.571 × 10²⁷ molecules) has 4 significant figures, so our answer must have the same. For the number we calculated, that is the ones place. The 9 in the tenth place tells us to round the 9 in the ones place up to a 0, then the 2 in the tens place up to a 3.

[tex]5930 \ mol \ CH_4[/tex]

We must add a placeholder zero in the tenth place to reach 4 sig figs.

[tex]5930.0 \ mol \ CH_4[/tex]

The adult cow produces approximately 5930.0 moles of methane in a year.

Answer:

A Type IV PFD is an approved device designed to be thrown to a person in the water. It is not designed to be worn. It is designed to have at least 16.5 pounds of buoyancy. The most com- mon Type IV PFD is a buoyant cushion.

As illustrated from law of multiple proportion, the mass of the oxygen which combined with a fixed mass of the sulphur is in simple whole number ratio of 2 is to 3 (2:3).

The law of Multiple proportion states that when two elements combine to form more than one compound, the mass of the second element, which combines with a fixed mass of the first element, will always be ratios of small whole numbers.

To illustrate the law of multiple proportion from sulphur and oxygen, we use the given compounds.

The reaction of oxygen with sulphur to form SO₂ and SO₃:

[tex]S \ + \ O_2 \ -----> SO_2\\\\2SO_2 \ + \ O_2 \ ---> \ 2SO_3[/tex]

atomic mass of oxygen = 16 g

atomic mass of sulphur = 32 g

mass of sulphur = 32 g and mass of oxygen = (2x16) = 32 g

mass of sulphur = 32 g and mass of oxygen = (3 x 16) = 48 g

Notice, while mass of sulphur is constant, mass of oxygen changed.

The ratio of mass of oxygen in the given two compounds = 32g : 48g = 2:3

Thus, based on the law of multiple proportion, the mass of the oxygen which combined with a fixed mass of the sulphur is in simple whole number ratio of 2 is to 3 (2:3).

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Answer:

The international system of units is basic on 7 units.

Answer:

https://swartzbiotechnologylab.sites.stanford.edu/research

Explanation:

Alkyl chlorides and alkyl bromides are typically transformed into alkyl fluorides in the organic reaction known as the Swarts Reaction.

Frederick Jean Edmond Swarts first reported this procedure in 1892. Heating the alkyl chloride or alkyl bromide in the presence of heavy metal fluorides like AGF, Hg2F2, CoF2, or SbF3 causes this reaction.

Swartz process can be used to modify work for bacteria. Bacterial biofilms are collections of microorganisms where the cells are immersed in an extracellular polymeric matrix that the bacteria have self-produced.

In contrast to planktonic bacteria, which are in a state of free movement in a bulk solution, this situation is very different.

Applications:

Therefore, Alkyl chlorides and alkyl bromides are typically transformed into alkyl fluorides in the organic reaction known as the Swarts Reaction.

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Ozone O₃ consists of a strong reactive gas made up of three atoms of oxygen. Ozone occurs on the Earth as natural and man-made gas.

Ozone impacts life on Earth in positive or harmful ways depending upon its location in the atmosphere.

From the information given, we are to balance the reactant and the product that leads to the formation of Ozone by following each step.

Step 1:

2Cl° + 2O₃           2ClO°        +        2O₂

                          Chlorine               molecular

                          monooxide            oxygen

Step 2:

2ClO°                  ClOOCl

Step 3:

ClOOCl     + sunlight   →    2Cl°      + O₂

(b)

The Overall balanced equation can be expressed as:

2O₃    →    3O₂

Therefore, from the above explanation we can see the step by step process for the balanced equation and the overall balanced equation.

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Answer:

A. The relationship between the Sun,Moon,and Earth

Explanation:

Answer:

Copper (Cu), chemical element, a reddish, extremely ductile metal of Group 11 (Ib) of the periodic table that is an unusually good conductor of electricity and heat. Copper is found in the free metallic state in nature.

Explanation:

hope this helps:)

Answer:

radiation

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.hi how r u

Is my answer correct

Answer:

Radiation

Explanation:

Heat from the sun reaches is by the process of radiation

Answer:

Reha should apply 540 N to lift Neha.

Explanation:

L = 360 N

LD  = 60 m

E =?

ED = 40m

NOW

L * LD = E * ED

360 *60 = E*40

21600/40 = E

540 N = E

Answer:

[tex]\boxed {\boxed {\sf 2.3 \ g/mL}}[/tex]

Explanation:

We are asked to find the density of a rock. Density is the substance's mass per unit volume. The formula for calculating density is:

[tex]\rho= \frac{m}{v}[/tex]

The mass of the rock is 23 grams. The volume was found using water displacement. A known amount of water was measured, the rock was added to the graduated cylinder, and the water level was recorded again. The volume is the difference between the final and initial water level. The graduated cylinder originally had 20 milliliters and the water rose to 30 milliliters.

Now we know the mass and the volume.

Substitute the values into the formula.

[tex]\rho= \frac{ 23 \ g }{30 \ mL}[/tex]

Divide.

[tex]\rho= 2.3 \ g/mL[/tex]

The density of the rock is 2.3 grams per milliliter.

Answer:

By filtering

Explanation:

Take one cup of mixture of sand and water , filter using a cotton cloth ,

Answer:  80 grams

Explanation:  

2KMnO4 -> K2MnO4+MnO2+O2​

2 moles of KMnO4 would produce 1 mole of MnO2, so 1 mole of KMnO4 would produce 0.5 moles of MnO4.  The molar mass of MnO4 is 160 g/mole.  1/2 mole of KMnO4 would therefore be (160 g/mole)*(0.5 moles) = 80 grams.

Answer:

Since hydrogen has a single electron in its valence shell, it exhibits dual nature. of the periodic table, or it can obtain one electron to complete its valency of two, such as halogens from Group 17. Since it only has one electron in its outer shell, hydrogen has a dual existence.

Explanation:

This means that, like a normal halogen, a hydrogen atom can easily gain an electron to form a complete outer shell, or lose an electron to form an alkali metal. Since it already has two electrons in its outer shell, hydrogen can be diatomic, rendering it unreactive.