The scientific study of the behavior of substances near 0 k is called pyrogenics. True false.

ΔU of the reaction the combustion of compound x is -538 kJ/mol

Combustion is a reaction in which a substance reacts with oxygen gas and releasing energy in the form of light and heat

Here given data is

Mass of compound x = 0.485gram

Mass of water = 3000gram

Temprature rise =  0. 285°C

Heat capacity of the calorimeter = 3. 81 kJ/°C

Specific heat of water =  4. 184 J/g·°C

MW of x = 56. 0 g/mol

Then calculate q

ΔU = ΔH -PΔV

The bomb calorimeter has a constant volume ΔV = 0

ΔU = ΔH

q reaction = q(water + q(bomb)

q(bomb) = 3810J/°C×0.285 = 1085.85J

q(water) = 3000g × 4. 184 J/g·°C×0.285°C = 3577.32 J

q reaction = q(water) + q(bomb)

q reaction = 4663.17 J = 4.66kJ means this is an exothermic

Then calculate moles of compound

Moles = mass/molar mass

Moles = 0.485 g/56.0g/mol

Moles = 0.00866 moles

Then calculate ΔU

ΔU = 4663.17 J/0.00866 moles = 538472 j/mol = 538.5kJ/mol means the reaction is exothermic

ΔU = -538kJ/mol

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The mass of zinc that the company can expect to produce is 5g.

The reaction is given as follows:

Ca + ZnCO₂ → Zn + CaCO₃

15g       25g      ? g        35g

To find: mass of zn

The above given reaction is an example of a displacement reaction.

According to law of conservation of mass, in a chemical reaction the mass of reactants is equal to the mass of products.

Here, mass of reactants

= mass of Ca + mass of ZnCO₂

= 15g + 25g

mass of products

= mass of Zn + mass of CaCO₃

=mass of Zn + 35g

∵ mass of reactants = mass of products

⇒ 15g + 25g= mass of Zn + 35g

⇒mass of Zn = (15+25)g - 35g

⇒mass of Zn = 40g- 35g

⇒mass of Zn = 5g

Hence, 5g of Zinc is expected to be produced.

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The bond order for H2- and H2+ is calculated using the molecular orbital (MO) diagram.

Bond order: what is it?

If a molecule contains more than two atoms, the bond order must be determined by-

If there is no order in the bonds, molecules cannot form.

Create a schematic of the molecular orbitals (MO). As one electron is contributed by each hydrogen atom, H2 + has one electron while H2 - has three.

The result of calculating their bond order is:

Bond Order H 2+ = 1/2 x ( Bonding Antibonding ) = 1 /2 x ( 1 0 ) = 1 /2

Bond Order H 2- = 1/ 2 x ( Bonding Antibonding ) = 1/2 x ( 2 1 ) = 1/2 x 1 = 1/2

Both are equally stable, so neither is more so. However, they are unavoidably less stable than H2 .

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Answer:

Explanation:

Answer:: 1100 j

Explanation:

Solid aluminum has a specific heat capacity of 0.90 J/ gK joules of heat are absorbed to raise the temperature of 24.0 grams of aluminum from 300. K to 350. K is 11.080 J

Heat is the transfer of kinetic energy from one medium or object to another from an energy source to a medium or object

Here given data is

Specific heat capacity = 0.90 J/gK

Temperature = 300. K to 350. K = 350 - 300 = 50 K

Mass =  24.0 grams

We have to calculate the heat = ?

Q =mCΔT

Q =  24.0 grams× 0.90×50 K

Q = 11.080 J

11.080 J  heat are absorbed to raise the temperature

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Using the regression equation, the concentration of a sample with an absorbance of 0.25 is 1.76*10^-5M

Using the regression equation obtained from the model,

y = 15200x - 0.018

y = absorbance. x = Concentration

Concentration of unknown dye sample with absorbance of 0.25:

Substitute the absorbance value y = 0.25 into the equation and calculate the concentration x:

0.25 = 15200x - 0.018

side

15200x = 0.25 + 0.018

15200X = 0.268

Division by 15200

x = (0.268 ÷ 15200)

x= 1.76*10^-5M, which is the concentration of the sample.

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The phase change that is exothermic is option A: condensation

The molecules give up their thermal energy during condensation. Exothermic refers to the process where molecules release heat energy. Exothermic condensation would result. Keep in mind that thermic refers to "heat," while exo means "to leave."

Note that The best illustration of condensation—where water vapor transforms back into liquid water—are those huge, fluffy clouds hovering above your head. Additionally, as the water droplets in a cloud unite, they grow sufficiently heavy to create raindrops that can fall directly upon your head.

Therefore, While freezing, condensation, and deposition are exothermic processes, fusion, vaporization, as well as sublimation are endothermic processes. Phase changes, also known as phase transitions, include changes in state.

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Physical change does not alters the molecule or atoms that are present.

Physical changes are those changes that do not alter the identity of the molecules or atoms that are taking part in the chemical reaction. Or we can say that physical changes are changes in which no bonds are broken or formed. This means that the same types of compounds or elements that were present  at the beginning of the change are there at the end of the change as well. Because the ending materials are the same as the beginning materials, the properties (such as color, boiling point, etc.) will also be the same. Physical changes also  involve moving molecules around, but not changing them.

Whereas Chemical changes occur when bonds are broken and are formed between molecules or atoms. This means that one substance with a certain set of properties (such as melting point, color, taste, etc) is turned into a different substance which have different properties. Chemical changes are frequently harder to reverse than physical changes.

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Answer: amorphous

Explanation:

Amorphous solids don't have an organized structure and therefore don't have a definite melting point. They slowly soften and melt as the temperature increases.

The heat capacity of calorimeter is 133.76 J/c.

What is calorimeter?

A calorimeter is a device used in calorimetry, a procedure for calculating heat capacity and trying to measure the heat of chemical reactions or even other physical changes. Among the most popular kinds are dsc calorimeters, isothermal micro calorimeters, titrimetric calorimeters, and accelerated rate calorimeters. A straightforward calorimeter is just a metal container with a thermometer suspended beyond a combustion chamber. It's one of the measurement tools used in the research of chemistry, biochemistry, and thermodynamics. The two substances A and B are separately added to a calorimeter, and the original and final temperatures are recorded, in order to determine the enthalpy change per mole of substance A in a reaction between those two substances.

We know:

mw Cw Ow = mc Cc delOc + Ccal delc

80g * 4.18/gc * (80-45)C = 80g * 4.18J/g * (45-20) + Ccal *(45-20)

= 11704J = 8360 + Ccal (25)

= 133.76 j/c

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True each element possesses unique physical and chemical properties.

An element's properties are based on its atomic numbers, atomic masses, and electron configurations. An element is a pure substance consisting of only one type of atom which all have the same number of protons in their nuclei. A substance whose atoms all contain the same number of protons is said to be an element; alternatively, all the atoms of a particular element must contain the same number of protons. Chemical reactions cannot degrade elements because they are the simplest chemical forms. The two main classes of elements are metals and non-metals.

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KClO₂, NaC₂H₃O₂, LiBrO, and LiCN will form basic solutions.

How is a basic solution formed?

A basic solution can be created easily. A solid base is dissolved in water to create a basic solution. Water reacts with some solid bases as a result, producing hydroxide ions. For instance, when water (H2O) is exposed to NaOH, the reaction results in Na+ and OH-.

LiBrO in an aqueous solution is basic. This conjugate base creates hydroxide ions when it is in equilibrium with the water.

Salt that is basic is NaC₂H₃O₂. Salts produced by the interaction of a strong base and a weak acid are typically basic. The solution will be basic.

The potassium ion in KClO₂ does not hydrolyze in water. Due to the ionization of ClO−2 C l O 2 − hydroxide ions are formed. This results in a solution with a basic pH value. Similarly, LiCN is also basic in water.

Hence, the answer is all of the above.
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To learn about the saturated solution and concentration to find the value of Ksp.

What is saturated solution?

When a solution has dissolved all of the solute it is capable of removing, it is said to be saturated. At a certain temperature, a saturated solution cannot dissolve any more solute. We can create a saturated solution by continuing to dissolve the solute until no more can be done.

What is concentration?

In chemistry and related fields, the idea of concentration is used frequently. It is a way to gauge how much of one substance is incorporated into another.

The ionic compound lead(II) chloride, or PbCl2, does not completely dissociate into lead(II) cations and chloride anions when placed in aqueous solution.

Instead of completely dissociating, a state of equilibrium will be established between the solid lead (II) chloride and the dissolved ions under the control of the solubility product constant, K sp.

PbCl 2(s) + 2 Cl (aq] Pb 2 + (aq]

The compound's molar solubility, or s in moles, represents the amount of lead(II) chloride that will dissolve in aqueous solution at a given temperature.

A mole of lead II chloride will result in the production of 1 mole of lead II cations and 2 moles of chloride anions. To determine the molar solubility of the solid, use an ICE table.

PbCl 2(s) + 2 Cl (aq] Pb 2 + (aq]

I      0        0

C     (+s)     (+2s)    

E      s          2s

According to the definition, the solubility product constant will equal

Ksp = (pb²⁺) (cl⁻)²

Ksp = s⋅ (2s)²= 4s³

As a result, lead (II) chloride will have a molar solubility of

4s³=1.6⋅10⁻⁵⇒ s= [tex]\sqrt[3]{1.6/4*10^-5}[/tex] = 0.0159 M.

Therefore, the value of ksp for pbcl2 at this temperature is 0.0159 M.

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The quantity weak acid present in solution is equal to the quantity of conjugate base created at the half equivalence point.

For weak acid/strong base titrations, the pH at the equivalence point is >7. This is because the solution consists of water, strong base (neutral) cations, and weak acid (base) anions. The pH at half the equivalence point volume (half the equivalence point) is the pKa.

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There are 3 major steps involved in the mechanism of acid-catalyzed hydration of propene they are formation of carbocation, nucleophile attacks on carbocation and Deprotonation to form alcohol.

Acid catalyzed hydration is the process of breaking of a pi bond in an alkene or alkyne so that water can be added. It is an electrophilic hydration reaction because the water molecule acts as an electrophile once it has been protonated by the acid. It is an acid-catalyzed reaction because the acid, such as sulfuric acid, acts as a catalyst here.

There are 3 major steps involved in the mechanism of acid-catalyzed hydration of propene. They are as follows;

1. Carbocation formation from propene which is formed by attack of [tex]H_3O^{+}[/tex] ion.

2. In the next step nucleophile attacks the carbocation that is formed.

3. Next step is deprotonation takes place where water molecule is removed to form respective alcohol that is propanol

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Learn more about distillation and condensation process.

What is distillation?

Distillation is a process in which a liquid is transformed into a vapor and then condensed back into a liquid state. The simplest illustration of it is when distilled water drops are left on a chilly surface after being deposited as steam from a kettle.

What is condensation?

The process by which matter transitions from its initial gaseous form into its liquid state is known as condensation. For instance, condensation happens when airborne water vapor (in its gaseous form) makes the transition to liquid water upon coming into contact with a cooler surface.

Given density of isoamyl acetate = 0.88g/ml

volume of isoamyl acetate = 75 ml

MW of  isoamyl acetate = 130.2g/ml

Therefore, no.of moles =mass/ molar mass

and mass = density*volume

Therefore, no.of moles = density*volume/molar mass

= 0.88g/ml*75 ml/130.2g/ml

=0.55 moles

similarly for methyl benzoate

no. of  methyl benzoate = 1.09g/ml*115ml/136.2gml

=0.92 moles.

Boiling point of isoamyl acetate = 142°c (vaporize first)

Boiling point of methyl benzoate= 199.6°c (moves down)

mole fraction of isoamyl acetate = 0.51/0.57+0.92

=0.357

mole fraction of the methyl benzoate = 0.643

%of isoamyl acetate= 35.7%

%of methyl benzoate= 64.3%

mole ratio= 35.7:64.3

Initial boiling point 166°c

composition of vapor in equilibrium with liquid  75: 25 (using theoretical plate1)

                                                                                ↓     ↓

                                                                              IA      MB

Re vaporization at 145°c

composition of vapor, at 145°c

95:5 ( using theoretical plate 2)

↓     ↓

IA MB

Condensate⇒ low density mixture

% composition of Condensate= 95%

(IA) using two theoretical plates

Therefore, Condensate is 95%

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Substances with weak intermolecular forces will have higher vapor pressure

Vapor pressure is the measure of the tendency of a material to change into the gaseous or vapor state, and it increases with temperature. So, the temperature at which the vapor pressure at the surface of a liquid becomes equal to the pressure exerted by the surroundings is called the boiling point of the liquid. Or we can simply say that the when a liquid is boiling its vapor pressure is equal to the external pressure.

In the above given case we are comparing the intermolecular forces and understanding the concept of vapor pressure. So, vapor pressure of liquid is said to be  inversely proportional to the intermolecular forces between the atoms of the liquid. This relation means that if the liquid has stronger intermolecular forces than the rate of evaporation of liquid will be very low and hence it causes lower vapor pressure.

But whereas if the  intermolecular forces are weaker then the rate of evaporation of the liquid will be high and therefore it vaporizes fast which results in higher vapor pressure.

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In order to use a flashlight to see in the dark, the flashlight must first transform the electrical energy it receives from batteries into light energy.

What is flashlight?
A portable hand-held electric lamp is known as a torch (UK, Australia), or a flashlight (US, Canada). The light source used to typically be a tiny incandescent light bulb, but since the mid-2000s, light-emitting diodes (LEDs) have taken their place. A typical flashlight is made up of a light source mounted inside a reflector, a transparent cover to shield the light source as well as reflector, a battery, a switch, and sometimes a lens. All of these components are housed in a case. Around 1899, the development of dry cells and tiny incandescent electric lamps made the first battery-operated flashlights feasible. Today's flashlights run on disposable as well as rechargeable batteries and mostly use light-emitting diodes. Some require the user to turn a crank, shake the lamp, or squeeze it in order to operate. Some batteries can be recharged using solar panels.

In order to use a flashlight to see in the dark, the flashlight must first transform the electrical energy it receives from batteries into light energy. This light energy is then emitted from the flashlight in a concentrated beam, which illuminates the area in front of the person using the flashlight and allows them to see in the dark.

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The mass of the products when 5g of a chemical A is combined with 5g of chemical B is 10g.

The law of conservation of mass is a law of classical physics that states that the total mass of a closed system remains constant regardless of the chemical or physical changes that take place within it.

The law explains that a mass in an isolated system can neither be created nor be destroyed but can be transformed from one form to another”.

This means that in a chemical reaction, the mass of the reactants must be equal to the mass of the products.

According to this question, chemical A has a mass of 5 grams and chemical B has a mass of 10 grams. If these two chemicals are mixed and a complete chemical reaction occurs, the total mass of the products in accordance with the law of conservation of mass is 5g + 5g = 10 grams.

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Vapor pressure will increase with Temperature.

What does vapor pressure mean exactly?

The vapor pressure of a liquid is the pressure at which a vapor and its liquid (or solid) are at equilibrium, or the pressure at which a sample of a liquid (or solid) evaporates in a closed container to produce a vapor.

Vapor pressure for liquids is influenced by the following variables: Intermolecular Force and Temperature

The molecules of a liquid begin to move more quickly as the temperature rises. More vapor pressure is produced as a result of the production of gas. As a result, vapor pressure and temperature are directly related. The related graph will be a straight line graph since temperature and vapor pressure are directly proportional to one another.

Hence, Vapor pressure will increase with Temperature.

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Answer:

James Hutton described the Law of Inclusions, which states that if one rock body (Rock B) contains fragments from another rock body (Rock A), then Rock B must be younger than the bits of rock it has.Garnets commonly contain many inclusions

The mole of oxygen are formed from KMNO3 is 0.724 mol.

calculation:-

Given the mass of KNO3 KNO3 is 82.5g

The molar mass is 101.11 g/mol.

Mole of KNO3 = 82.5g/ 101.11 g.

0.724 mol

From the balanced equation, it is clear that for every 1 mole of KNO3 K N O 3 = 54 moles of oxygen are required.

Therefore, 0.724 mol of oxygen is required for forming 82.5 g of KNO3 KNO 3.

The formula mass of a substance is defined as the sum of the atomic masses of the atoms that make up the ionic compound. It is generally used for ionic compounds that do not contain individual molecules but contain ions as building blocks. Mass can be defined as a measure of the amount of matter in the body. Weight is a measure of weight acting on the mass. The SI unit of mass is the kilogram.

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The energy of combustion for 1 gm of the hydrocarbon is 0.56 kJ

What is a bomb calorimeter?

Bomb Calorimeter is a constant-volume  calorimeter which  measures the heat of a particular reaction or measures the calorific value of the fuels. They can withstand  large pressure produced within the calorimeter due to the reaction or burning of fuel.

The above question can be solved by

Energy of combustion = m X c X ΔT

m = mass of hydrocarbon burnt  ,

 c = heat capacity of calorimeter   ,

 ΔT = temperature change

Energy of combustion = 0.106g X 2.47kJ/K X 2.14K = 0.56kJ

Energy of combustion when 1g of hydrocarbon is burnt = (0.56kJ / 0.106g ) X 1g = 5.28kJ

Hence,  The energy of combustion for 1 gm of the hydrocarbon is 0.56 kJ

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The mass of Magnesium carbonate is 0.275 g.

The balanced chemical reaction is shown below,

Na₂CO₃ + Mg(NO₃)₂ → 2 NaNO₃ + MgCO₃

0.200 M   0.0650 M                                        ?

10.0           5.00 mL                                          ?

Since the volume and concentration of Mg(NO₃)₂ and Na₂CO₃ is given, we can calculate the number of moles for each of them and then determine the limiting reagent.

Convert the volume of  Mg(NO₃)₂and Na₂CO₃ to liters:

5.00 mL x ( 1 L/1000 mL ) =   5.00 x 10⁻³ L

10.00 mL x ( 1L/ 1000 mL ) = 1.000 x 10 ⁻² L

Number of  mol Mg(NO₃)₂ = (0.0650 mol /L) x 5.00 x 10⁻³ L

                                            = 3.25 x 10⁻⁴ mol Mg(NO₃)₂

Number of mol Na₂CO₃ = (0.200 mol / L) x 1 x 10⁻² L  

                                        = 2.000 x 10⁻³  mol Na₂CO₃

Limiting reagent = 3.25 x 10⁻⁴ mol Mg(NO₃)₂ x ( 1 mol Na₂CO₃ / mol  Mg(NO₃)₂ )

                           = 3.25 x 10⁻⁴ mol  Na₂CO₃ required .

Limiting reagent is Mg(NO₃)₂ since 2.25 x 10⁻⁴ mol  Na₂CO₃ is required to

react completely with  2.25 x 10⁻⁴ Mg(NO₃)₂, and there is an excess.

Number of moles of MgCO₃ produced is calculates as follows:

= 3.25 x 10⁻⁴ mol  Mg(NO₃)₂ x ( 1 mol MgCO₃ / 1 mol Mg(NO₃)₂ )

= 3.25 x 10⁻⁴ mol  MgCO₃

The formula for calculating number of moles is given as :

Mole = mass/molar mass

⇒ Mass= Mole × molar mass

Mass = 3.25 x 10⁻⁴ mol  MgCO₃ x   84.31 g/mol

         = 0.275 g

Hence, the mass of MgCO₃ is 0.275 g

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Explanation:

Absolute zero is the temperature at which particles have theoretically zero kinetic energy.

The higher temperature of the hot tea means that the water molecules in the tea will move faster on average than the water molecules in ice cream.

A scientific law is different from a scientific theory because it describes something in nature without attempting to explain it, this statement is true.

A scientific law foretells the outcomes of particular beginning circumstances. It may tell you what color hair your unborn kid would have or how far a baseball will go when fired at a specific angle.In contrast, a theory seeks to offer the best plausible justification for why events take place the way they do.

A scientific law often describes an observable phenomena. It doesn't explain the phenomenon's existence or its origins. A scientific theory is the explanation for a phenomena. It is untrue that with enough study, hypotheses become laws.

Thus, a scientific law is different from a scientific theory because it describes something in nature without attempting to explain it, this statement is true.

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The mechanical advantage of the lever that has a 36 cm input arm and a 6 cm output arm is 0.167.

Mechanical advantage is the ratio of the output force produced by a machine (especially a simple machine) to the applied input force.

This means that mechanical advantage of a machine can be calculated by dividing the output force by the input force as follows:

MA = Fb/Fa

Where;

According to this question, a lever has a 36 cm input arm and a 6 cm output arm. The mechanical advantage can be calculated as follows;

MA = 6cm ÷ 36cm

MA = 0.167

Therefore, 0.167 is the mechanical advantage of the lever.

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Answer:

The first 20 Elements of the Periodic Table: Hydrogen, Helium, Lithium, Beryllium, Boron, Carbon, Nitrogen, Oxygen, Fluorine, Neon, Sodium, Magnesium, Aluminium, Silicon, Phosphorus, Sulphur, Chlorine, Argon, Potassium, Calcium.

Explanation:

hope this helps:)

The first 20 Elements of the Periodic Table are given below:

What is an element?

A chemical element is a type of atom with a particular number of protons in the nucleus, such as the specific compound made up entirely of that species. Chemical elements, unlike chemical compounds, cannot be broken down into simpler substances by any chemical reaction. The number of protons in the nucleus is an element's defining attribute, and it is symbolised by the symbol Z - all atoms with the same atomic number are atoms of the same element. Atoms are rearranged into new compounds linked together by chemical bonds when various elements undergo chemical reactions.

The first 20 Elements of the Periodic Table are given below:

Hydrogen (atomic number 1), Helium (atomic number 2), Lithium (atomic number 3), Beryllium (atomic number 4), Boron (atomic number 5), Carbon (atomic number 6), Nitrogen (atomic number 7), Oxygen (atomic number 8), Fluorine (atomic number 9), Neon (atomic number 10), Sodium (atomic number 11), Magnesium (atomic number 12), Aluminium (atomic number 13), Silicon (atomic number 14), Phosphorus (atomic number 15), Sulphur (atomic number 16), Chlorine (atomic number 17), Argon (atomic number 18), Potassium (atomic number 19), Calcium (atomic number 20).

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Answer:

Bromine has 7 electrons but to complete the octet you add one more electron so it has a net charge of 1-

Explanation:

For the student who is reacting magnesium and hydrochloric acid by placing a strip of Mg metal into a beaker containing HCl solution, the rate of reaction between the Mg and the HCl will be increased by:

The rate of a chemical reaction is the rate at which the reactant molecule is converted or the rate at which product molecules are formed.

Mathematically;

The factors that affect the rate of a reaction are:

In the given reaction, the surface area of the reactants can be increased by cutting the magnesium metal strips into smaller pieces thus, increasing the reaction rate.

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Answer:

It C smh smh

Explanation:

Usatest prep and expert explanation