A 45-kg boy pulls a wagon with a force of 38 N for a distance of 550 m. If the boy
takes 240 s, what is the power expended by the boy?

Answer:

Formaldehyde is highly soluble in water.

Explanation:

Formaldehyde is the simplest of the aldehydes (R−CHO) it is an organic compound which occurs naturally with the formula H−CHO. . The IUPAC name of formaldehyde is methanal.

Formaldehyde  at room temperature is a colorless gas and the liquid is invisible or like white-water. Formaldehyde has an irritating and very pungent like odour. Formaldehyde is very soluble in water.

Now according to Henry's constant law (3 × 10-5 kPa·m3/mol) Formaldehyde will be very unlikely to volatilize from water.and hence, Formaldehyde is considered to be highly soluble in water.

Answer:

1. The resulting mixture was cloudy.

Explanation:

There are 5 observations that can be observed when a chemical change takes place:

1. Color change.

2. Temperature change.

3. Formation of precipitate.

4. Production of gas.

5. Light Emission.

1st option clearly implies that a precipitate has been formed, which according  to the 3rd point as mentioned above is an evidence of a chemical change.

3rd option shows a color change but is not the best evidence because it might also be that dilution has taken place, which isn't a chemical change. Hence, it isn't the best evidence.

Therefore, 1st option is the best choice.

3 The resulting liquid was light blue.

Of the ten characteristics of chemical reactions, the occurrence of color changes is the characteristic that is most easily seen and known quickly, so the third choice is the most appropriate answer.

Chemical changes are changes in a substance or material that causes the formation of new substances. The characteristics of chemical change are: new types of substances are formed, substances that change cannot return to their original form, followed by changes in chemical properties through chemical reactions. During chemical changes, the mass of the substance before the reaction is the same as the mass of the substance after the reaction.

Different chemical reactions are used together in chemical synthesis to produce the desired compound product. In biochemistry, a series of chemical reactions are catalyzed by enzymes to form metabolic pathways, where synthesis and decomposition that are normally not possible in cells are carried out.

Chemical properties are properties for which chemical changes are needed.

The nature of matter tends to carry out chemical reactions, including:

Characteristics of Chemical Reactions

Here are ten characteristics of chemical reactions that are most easily observed.

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Grade: Middle School

Subject: Chemistry

keywords: Chemical changes, characteristics of chemical reactions

Answer:

A.) A substance that oxidizes another substance

Explanation:

An oxidizing agent always oxidize another substance by either accept electron, removing electronegative elements or adding electropositive elements to the substance.

Answer:

This is called a "cell wall'.

Explanation:

Answer: cell wall

Explanation:

Answer:

The answer for this question is option D

Answer:

The frog has 4 toes on each foot in the front, and 5 toes on each foot in the back.

Explanation:

Sodium Chloride (NaCl) can be classified as a salt

Explanation:

Sodium chloride is an "ionic compound" is known as salt. The ratio in which the  sodium(Na) and chloride(Cl) present in sodium chloride in  NaCl is  1:1. It is found in seawater and is accountable for the salinity of the seawater. Also, NaCl is the extracellular fluid for various multicellular organisms.  

When refined, it becomes in its 'edible' form and is used in food preservatives. Whereas, the large quantity of sodium chloride is used in various industries.  

Answer:

25.157 cm³

Explanation:

Data Given:

Mass of Sugar (m) = 40g

Density of sugar given in literature = 1.59 g/cm³

Volume of Sugar = ?

The formula will be used is

                              d = m/v ........................................... (1)

where

D is density

m is the mass

v is the volume

So

Rearrange the Equation (1)

                              d x v = m

                               v = m/ d         ................................................ (2)

put the given values in Equation  (2)

                       v = 40g / 1.59 g/cm³

                       v = 25.157 cm³

volume of 40 g of sugar = 25.157 cm³

Final answer:

To calculate the volume of 40g of sugar, divide the mass by the substance's density, which is not provided in the question. An example calculation with a hypothetical density of 1.59 g/cm³ gives a volume of approximately 25.16 cm³.

Explanation:

The volume of a substance can be calculated using its mass and density. To calculate the volume of 40g of sugar, we need to know the density of sugar. Unfortunately, the density is not provided in the question. However, we can use the method of conversion once the density is known. If the density of sugar was, for example, 1.59 g/cm3 (which is hypothetical in this case), the volume would be calculated as follows:

Volume = Mass / Density

Volume = 40g / 1.59 g/cm³

Volume ≈ 25.16 cm³

Ensure to substitute the correct density value of sugar in the same units to get the accurate volume.

Answer:

1. Robert Bunsen hence being called the bunsen burner. 2. William Kirchhoff

Explanation:

Answer:

CBrClF₂  

Explanation:

You list the halogens in alphabetical order and  use a subscript 2 to show that there are two F atoms.

The formula is CBrClF₂.

The name of the compound is bromochlorodifluoromethane.

Answer:

The charges repel each other

Explanation:

Answer:

Fe → Fe⁺³ + 3e⁻

Explanation:

The oxidation half reaction for iron is:

Fe → Fe⁺³ + 3e⁻

Other options are incorrect because,

A) 3e⁻ + Fe  →   Fe³⁺

This is incorrect because when three electrons are gained by any atom it will gain negative three charge not positive.

C) 6e⁻ + 2Fe →  2Fe³⁺

This is incorrect because when six electrons are gained by any atom it will gain negative six charge not positive.

d) Fe →  2Fe³⁺ + 6e⁻

Its also incorrect because iron atoms are not balanced on both side of equation.

Answer:

c

Explanation:

Answer:

The correct option is B) Decomposition.

Explanation:

In a decomposition reaction, a single substance decomposes, producing two or more different substances. That is, two or more substances are formed in this type of reactions from a compound. The atoms that form a compound are separated to give the products according to the formula:

AB → A + B

There are 3 types of decomposition reactions, depending on the external factor that can promote the decomposition of the molecule into simpler substances:

In this case a decomposition reaction occurs, where C₁₆H₁₇NaO₁₄ decomposes to give carbon dioxide (CO₂) and C₂H₃NaO₃.

Another option may have been chemical synthesis, which involves the combination of two or more substances and results in the formation of a substance.  But in this case you can see that the water does not react (it appears in the reagents and in the products). This means that it helps with the decomposition mentioned previously.

So, the correct option is B) Decomposition.

Answer:

a: 1st paragraph from the left side indicates Newton's first law.

b:, 2nd paragraph from the left side indicates Newton's third law.

c: 1st paragraph from right side indicates Newton's first law.

d: 2nd paragraph from right side indicates Newton's second law.

Explanation:

Answer:

Theoretical yield of Ca₃(PO₄)₂ = 19.67 g

Percent yield of Ca₃(PO₄)₂ = 11.4 %

Explanation:

Data given

Potassium Phosphate  K₃PO₄  = 30.00 g

calcium nitrate Ca(NO₃)₂ of 0.25 M  = 100.0 mL

Reaction given:

        2K₃PO₄(s) + 3Ca(NO₃)₂(aq) --------->  Ca₃(PO₄)₂(s) + 6KNO₃(aq)

Solution :

Part A :

To find the theoretical yield of Calcium phosphate

Look at the reaction :

             2K₃PO₄(s) + 3Ca(NO₃)₂(aq) ---------> Ca₃(PO₄)₂(s) + 6KNO₃(aq)

               2 mol          3 mol                               1 mol                6mol

 So,

2 mol of  2K₃PO₄ give 1 mole of Ca₃(PO₄)₂

if we represent mole in mass then

Molar Mass of K₃PO₄ =  3(39) + 31 + 4(16)

Molar Mass of K₃PO₄ =  212 g/mol

and

Molar mass of Ca₃(PO₄)₂  =  [ 3(40) + 2((31) + 4(16))]

Molar mass of Ca₃(PO₄)₂  =  [ 120 + 62 + 96] = 278 g/mol

Molar mass of Ca₃(PO₄)₂ = 278 g/mol

Now, if we write it in grams

  2K₃PO₄(s)    +      3Ca(NO₃)₂(aq) ---------> Ca₃(PO₄)₂(s)    +     6KNO₃(aq)

   2 mol                    3 mol                               1 mol                      6mol

  2 mol ( 212 g/mol)                                         1 mol (278 g/mol)

   424 g                                                               278 g

So from the above information we come to know that

    424 g of K₃PO₄ gives 278 g of Ca₃(PO₄)₂

then 30 g will give how much Ca₃(PO₄)₂ Calcium phosphate

Apply unity formula

    424 g of K₃PO₄ ≅ 278 g of Ca₃(PO₄)₂

       30 g of K₃PO₄ ≅ x g of Ca₃(PO₄)₂

By doing cross multiplication and rearranging the above values

      x g of Ca₃(PO₄)₂ = 278 g x  30 g / 424 g

      x g of Ca₃(PO₄)₂ = 19.67 g

So,

30 g of K₃PO₄ will give 19.67 g Ca₃(PO₄)₂ theoretically.

Theoretical yield of Ca₃(PO₄)₂ = 19.67 g

Now,

Part B :

To find percent yield of Ca₃(PO₄)₂

Solution

Data given:

       Actual yield of Ca₃(PO₄)₂ = 2.25 g

       Theoretical yield of Ca₃(PO₄)₂ = 19.67 g

Formula to be used:

         Percentage yield = Actual yield/ theoretical yield x 100 %

Put values in Above formula

       Percent yield = 2.25 g / 19.67 g x 100 %

       Percent yield =  0.1144 / 100 %

      Percent yield = 11.4 %

So,

Percent yield of Ca₃(PO₄)₂ = 11.4 %

Answer:

The solubility of a substance can be increased by increasing the amount of solvent in a solution.

Explanation:

Two ways by which the rate of dissolving for substance can be increased.

1 By increasing the temperature of the solution: Increase in temperature will in turn increase the entropy or disorder or randomness of the solute molecules in a solution thus increasing the rate of dissolving the substance in that solution.

2 By increasing the volume of the solution : increase in the volume of the solution by adding more solvent can also increase the dissolving rate of a specific substance in a solution.

To find the Cl- concentration of the dilute solution, calculate the moles of MgCl2 in the original solution, use stoichiometry to determine the moles of Cl-, and divide by the volume to find its concentration.

To determine the concentration of Cl- in the dilute solution, we can use the concept of mole ratios. First, we calculate the number of moles of MgCl2 in the original solution by multiplying the volume of the solution by its concentration. Then, we use the stoichiometry of the equation to determine the number of moles of Cl-. Finally, we divide the number of moles of Cl- by the volume of the dilute solution to find its concentration.

Moles of MgCl2 = volume of solution (L) x concentration of MgCl2 (mol/L)

Moles of Cl- = Moles of MgCl2 x 2 (from the balanced equation)

Concentration of Cl- = Moles of Cl- / volume of dilute solution (L)

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Answer:

Empirical formula is H₃PO₄

Explanation:

Given data:

Percentage of hydrogen = 3%

Percentage of P = 32%

Percentage of oxygen = 65%

Empirical formula = ?

Solution:

Number of gram atoms of H = 3 / 1= 3

Number of gram atoms of O = 65 / 16 = 4.06

Number of gram atoms of P = 32 / 31 = 1.03

Atomic ratio:

            H                      :      P                 :            O

           3/1.03               :     1.03/1.03      :         4.06/1.03

            3                      :        1               :              4

H : P : O = 3 : 1 : 4

Empirical formula is H₃PO₄.

Taking into account the definition of calorimetry, the specific heat of the unknown substance is 0.96 [tex]\frac{calories}{gC}[/tex].

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

Sensible heat is defined as the amount of heat that a body absorbs or releases without any changes in its physical state (phase change).

So, the equation that allows to calculate heat exchanges is:

Q = c× m× ΔT

where

In this case, you know:

Replacing in the expression to calculate heat exchanges:

-12 calories= c× 2.50 g× (-5 C)

Solving:

-12 calories÷ [2.50 g× (-5 C)]= c

0.96 [tex]\frac{calories}{gC}[/tex]= c

Finally, the specific heat of the unknown substance is 0.96 [tex]\frac{calories}{gC}[/tex].

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The specific heat of the substance is 0.96 cal/g°C, calculated by rearranging the formula q = mcΔT and substituting the known values for heat transferred, mass, and change in temperature.

The formula for calculating the specific heat (c) of a substance is:

q = mcΔT

where:

To find the specific heat, rearrange the formula to solve for c:

c = q / (mΔT)

In this example, the given values are:

Plugging in these values gives:

c = -12 cal / (2.50 g x -5°C)

c = 12 cal / (12.5 g°C)

c = 0.96 cal/g°C

The specific heat of the substance is therefore 0.96 cal/g°C.

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Final answer:

Chemistry tests like blood tests for plasma analysis generally use tubes containing K2EDTA, followed by centrifuging. Urinalysis, on the other hand, uses disposable test strips without prior sample preparation.

Explanation:

Chemistry tests that are not stat (immediate) are typically drawn in various types of tubes depending on the tests to be carried out. For tests that require plasma, blood samples are usually collected into tubes containing K2EDTA and then centrifuged to obtain plasma.

The plasma samples may sometimes be quenched with methanol before analysis. This is different from urinalysis, where physicians often use disposable test strips to measure the amounts of various substances in a patient's urine, without the need for any preparation before analysis. The diverse techniques and sample preparations in clinical chemistry underscore the importance of tailoring collection methods to specific tests, allowing for accurate and comprehensive diagnostic assessments in medical laboratories.

532 mg of hemoglobin

Explanation:

The concentration of hemoglobin in the blood is 15.2 g/dL. It we transform the g in mg and the dL in mL we have the value for the concentration to be 15200 mg / 100 mL.

Knowing the concentration we devise the following reasoning:

if there are         15200 mg of hemoglobin in 100 mL of blood

then there are            X mg of hemoglobin in 3.5 mL of blood

X = (15200 × 3.5) / 100 = 532 mg of hemoglobin

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Taking into account the definition of mass per volume concentration and the change of units, 532 milligrams of hemoglobin are in  every 3.50 mL of the patient's blood.

You know that the concentration of hemoglobin in the blood is 15.2 [tex]\frac{g}{dL}[/tex]. So, in first place, you need to change units: the g in mg and the dL in mL.

You know that 1 dL= 100 mL and 1 g= 1000 mg. Then:

[tex]\frac{15.2 g}{dL}=\frac{15.2*1000 mg}{100 mL} =152 \frac{mg}{mL}[/tex]

Then you can apply the following rule of three: if 1 mL contains 152 mg of hemoglobin, 3.5 mL contains how much mass of hemoglobin?

[tex]mass of hemoglobin =\frac{3.5 mLx 152 mg}{1 mL}[/tex]

mass of hemoglobin= 532 mg

Finally, 532 milligrams of hemoglobin are in  every 3.50 mL of the patient's blood.

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Answer:

space between particles

Explanation:

Properties of gases:

Molecule of gases randomly move everywhere and occupy all available space.

Gases don't have definite volume and shape and take the shape and volume of container in which it present.

Their densities are very low as compared to the liquid and solids.

Gas molecules are at long distance from each other therefore by applying pressure gases can be compressed.

The very weak inter molecular forces are present between gas molecules.

Properties of Liquid:

Liquid have definite volume but don,t have definite shape.

Their densities are high as compared to the gases but low as compared to the solids.

In liquid, molecules are close to each other and have greater inter molecular forces as compared to the gas molecules.

Properties of solids:

Solids have definite volume and shape.

In solids molecules are tightly pack and very close to each other.

Their melting and boiling point are every high.

The densities of solids are also very high as compared to the liquid and gas.

There are very strong inter molecular forces are present between solid molecules.

Answer:

B) K⁺, Sr²⁺ , O²⁻

Explanation:

Potassium is present in group one. It is alkali metal and have one valance electron.Potassium need to lose its one valance electron and form cation to get complete octet.

That's why it shows K⁺.

Sr is alkaline earth metal. It is present in group two. It has two valance electrons. Strontium needed to lose its two valance electrons and get stable electronic configuration.

When it loses its two valance electrons it shows cation with charge of +2.

Sr²⁺

Oxygen is present in group 16. It has sex valance electrons. It needed two more electrons to complete the octet. That's why oxygen gain two electron and form anion with a charge of -2.

O²⁻

The element with the electronic configuration 1s²2s²2p⁶3s²3p⁶4s²3d¹104p⁶5s²4d¹105p⁵ is Iodine (I).

The electronic configuration provided, 1s²2s²2p⁶3s²3p⁶4s²3d¹104p⁶5s²4d¹105p⁵, corresponds to the element Iodine (I). Iodine is a member of the halogen group, situated in group 17 of the periodic table. This halogen is commonly known for its use in antiseptics and as a necessary component of the human diet.

Group 7A (or VIIA) of the periodic table are the halogens: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). The name "halogen" means "salt former", derived from the Greek words halo- ("salt") and -gen ("formation").

Final answer:

The electron configuration corresponds to the element iodine (I), which is located in group 17 of the periodic table and has an atomic number of 53.

Explanation:

The electron configuration given in the question corresponds to an element's distribution of electrons across different orbitals. The full configuration is:

1s²2s²2p⁶3s²3p⁶4s²3d¹4p⁶5s²4d¹5p⁵

When assessing this electronic arrangement, we look at the last energy levels or shells being filled, which are 5s, 4d, and 5p. By looking at the periodic table, we can match this configuration to an element.

Considering that the 5p sublevel contains 5 electrons, we look at the p-block of the periodic table, in the fifth period (row). Counting in from the left of the p-block (taking into account the s-block and d-block orbitals which come before in the period), we find that the element iodine (I) matches this electronic configuration.

Therefore, the last electron enters the 5p subshell, and with 5 electrons in 5p subshell, confirms that the element is iodine (I).

Iodine is located in group 17, which comprises the halogens, and it has an atomic number of 53. Thus, the name of the element with the given electron configuration is iodine.

Answer:

Number of moles = 1.97 mol

Explanation:

Given data;

Number of moles of I₂ = ?

Mass = 500.0 g

Solution:

Number of moles = mass/ molar mass

Molar mass of  I₂ = 253.8 g/mol

Number of moles = 500 g / 253.8 g/mol

Number of moles = 1.97 mol

Answer:

Sunita will change the variable water.

Explanation:

Sunita have to change the variable water to perform this experiment of diffusion.This is because she is going to predict that more water she uses longer the time needed for the dye to spread through it.

 As a result she is increasing the amount of water to observe the effect of diffusible substance on diffusion with time.

Answer:

0.87 moles

Explanation:

Given data:

Number of moles of magnesium = ?

Number of atoms of magnesium = 5.23 × 10²³ atoms

Solution:

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

For example,

one mole = 6.022 × 10²³ atoms

5.23 × 10²³ atoms  × 1 mol / 6.022 × 10²³ atoms

0.87 moles

Answer:

Explanation:

Chemical equation:

HCl + Fe₂O₃  → FeCl₃ + H₂O

Balanced Chemical equation:

6HCl (aq)+ Fe₂O₃(s)  → 2FeCl₃(aq) + 3H₂O(l)

Ionic equation:

6H⁺(aq) + 6Cl⁻(aq) + 2Fe⁺³(aq) + 3O²⁻(aq) → 2Fe⁺³(aq) + 6Cl⁻(aq) + 3H₂O(l)

Net ionic equation:

6H⁺(aq) + 3O²⁻(aq) →  3H₂O(l)

The Cl⁻(aq) and Fe⁺³(aq) are spectator ions that's why these are not written in net ionic equation. The water can not be splitted into ions because it is present in liquid form.

Spectator ions:

These ions are same in both side of chemical reaction. These ions are cancel out. Their presence can not effect the equilibrium of reaction that's why these ions are omitted in net ionic equation.  

Answer: Electromagnetic waves are not like sound waves because they do not need molecules to travel. This means that electromagnetic waves can travel through air, solid objects and even space. This is how astronauts on spacewalks use radios to communicate. Radio waves are a type of electromagnetic wave.

Explanation:

Answer:

Electromagnetic waves can travel in vacuums.

Explanation:

Scientists use different types of telescopes to find and study supernovas. Some telescopes use visible light to observe the supernova's colors, while others study the X-rays and gamma rays dispersed in the explosion. These electromagnetic waves are used because electromagnetic waves can travel in vacuums, like space, whereas sounds waves cannot. In addition, the electromagnetic spectrum travels at the speed of light (much faster than sound waves), can be absorbed, and are not created by physical vibrations.

Answer:Convection powers the motion of the molten outer core. The hot liquid from deep inside rises toward the cooler top of the core. The movement transfers heat upward and causes a convective flow. Cooler liquid from near the core-mantle boundary sinks downward and thus also helps to power the convection.the outer core

Explanation:

Answer:

its b

Explanation:

i took the test :)