Here is a Answer to your question:
Air pollution is caused by solid and liquid particles and certain gases that are suspended in the air. These particles and gases can come from car and truck exhaust, factories, dust, pollen, mold spores, volcanoes and wildfires. The solid and liquid particles suspended in our air are called aerosols.
Here are the 8 causes of air pollution?
1: The Burning of Fossil Fuels
2: Industrial Emission
3: Indoor Air Pollution
4: Wildfires
5: Microbial Decaying Process
6: Transportation
7: Open Burning of Garbage Waste
8: Construction and Demolition
I am sorry if this was not helpful
Hope this was helpful
can you give me a real life example of a single replacement?
Answer:A single-replacement reaction is a chemical reaction in which one element replaces another in a compound. F₂ + 2NaCl → 2NaF + Cl₂, where F replaces Cl in NaCl. A double-replacement reaction is a reaction in which the metals in two ionic compounds exchange partners.
Which coefficients correctly balance the formula equation below? NH 4 NO 2 (s) N 2 (g)+H 2 O(l) A. 1, 2, 2 C. B. 2, 1, 2 D. 1, 2, 1 1, 1, 2
The coefficients which correctly balance the formula for the equation of reaction of NH₄ and NO₂ is 1,1,1,2.
What is a Balanced Chemical reaction?This is the type of reaction in which the atoms of the elements of the reactants equal that of the product.
The balanced reaction is seen below where 2 was added to H₂O so as to balance the atoms of oxygen on both sides.
NH₄ + NO₂ (s) ⇒ N₂ (g)+2H₂O(l)
Read more about Balanced Chemical reaction here https://brainly.com/question/15355912
Why is the addition of cold distilled water to the container holding the aspirin you are trying to isolate a necessary step and why should this step be carried out carefully?.
Answer:
The aspirin is more soluble in ethanol than water - the water helps the crystals separate from solution.
Explanation:
Hope this helps!
All materials are made of _____________.
A. Insulators
B. Atoms
C. Stuff
D. Conductors
Answer:
b atoms
Explanation:
everything is made up of atoms
Help ASAP!!! I need it now i have to write similar test tmrw
Answer and explanation:
(c)
A represents the activation energy (the minimum amount of energy needed to start a reaction).
B represents the overall change in energy (the difference between the energy of the reactants and products).
(d)
The reaction profile diagram shows that the reaction is exothermic because the energy change is negative (the products have less energy than the reactants) which shows that energy is lost or given out to the surroundings.
(e)
HCl gas doesn't conduct electricity, but hydrochloric acid does because in HCl, there are hydrogen ions that are free to move so they can carry a charge.
Hope this helps!
What factors might affect the amount of energy needed for
evaporation to occur and account for any differences between the temperatures
you observed?
6 important factors that affect evaporation are : 1. Wind assists evaporation; for example in clothes dry faster under a fan. 2. Heat assists evaporation; for example, in summer clothes dry faster than in winter.
Now have a free meme
From the table of available reagents select the one(s) you would use to convert cyclohexanone to the following compound:
A reagent is a compound that is used for the detection of the absence or presence of another substance.
What are reagents?Your information is incomplete as the available reagents aren't given. Therefore, an overview will be given.
Reagents are the integral part of a chemical reaction as they facilitate a reaction. A reagent is usually used tests.
Some typical examples of reagents include Tollens reagent, Fehling's reagent, Million's reagent, etc.
Learn more about reagents on:
https://brainly.com/question/5601219
The reagents that would be used to convert cyclohexanone to the following compound: hydrogen cyanide, potassium cyanide, and H₃O⁺, heat.
What is cyclohexanone?It is an organic compound with a chemical formula [tex]\rm (CH_2)_5 CO[/tex].
The cyclohexanone is used as Insecticides, paint and varnish remover, synthetic resins, etc.
It is not harmful to humans and animals, inhalation cause irritation.
Thus, the compound: hydrogen cyanide, potassium cyanide, and H₃O⁺, heat.
Learn more about cyclohexane
https://brainly.com/question/15593706
#SPJ4
How do I find the pH of two different solutions if they have the same number of moles?
Answer:
You can use a PH tester do identify the PH of each solution. Depending on what solutions ur testing, u shouldn't mix them as for there could be either a minor or bad chemical reaction
Explanation:
Using noble gas notation write the electron configuration for the silicon atom
Answer:
The closest noble gas to silicon is Neon (Ne)
Explanation:
Electron configuration is the distribution of the electrons in atomic and molecular orbitals. The electron configuration of silicon is [Ne] 3s² 3p².
What is electron configuration?An electron configuration is the allocation of the sub-atomic particle, an electron in the orbits of the atom or the molecules. It represents the distribution of electrons around the nucleus.
The general electron configuration of silicon with atomic number 14 is [tex]\rm 1s^{2}2s^{2}2p^{6}3s^{2}3p^{2}.[/tex] The noble gas closest to silicon is neon and can be written as, [tex]\rm [Ne] 3s^{2}3p^{2}.[/tex]
Therefore, the electron configuration of silicon is [tex]\rm [Ne] 3s^{2}3p^{2}.[/tex]
Learn more about electron configuration here:
https://brainly.com/question/20567097
#SPJ4
Salt is often added to water to raise the boiling point to heat food more quickly. if you add 30.0g of salt to 3.75kg of water, what will be the change in the boiling point of your salt water? what is the new boiling temperature? assume the kf of water is 0.512*c/m. i know the answer is 100.14 degrees i just need to know the work and how to get there, thank you!
Assuming an ebullioscopic constant of 0.512 °C/m for the water, If you add 30.0g of salt to 3.75kg of water, the boiling-point elevation will be 0.140 °C and the boiling-point of the solution will be 100.14 °C.
What is the boiling-point elevation?Boiling-point elevation describes the phenomenon that the boiling point of a liquid will be higher when another compound is added, meaning that a solution has a higher boiling point than a pure solvent.
Step 1: Calculate the molality of the solution.We will use the definition of molality.
b = mass solute / molar mass solute × kg solvent
b = 30.0 g / (58.44 g/mol) × 3.75 kg = 0.137 m
Step 2: Calculate the boiling-point elevation.We will use the following expression.
ΔT = Kb × m × i
ΔT = 0.512 °C/m × 0.137 m × 2 = 0.140 °C
where
ΔT is the boiling-point elevationKb is the ebullioscopic constant.b is the molality.i is the Van't Hoff factor (i = 2 for NaCl).The normal boiling-point for water is 100 °C. The boiling-point of the solution will be:
100 °C + 0.140 °C = 100.14 °C
Assuming an ebullioscopic constant of 0.512 °C/m for the water, If you add 30.0g of salt to 3.75kg of water, the boiling-point elevation will be 0.140 °C and the boiling-point of the solution will be 100.14 °C.
Learn more about boiling-point elevation here: https://brainly.com/question/4206205
which can provide the MOST energy in a ecosystem? a mushroom,coyote,a pine tree,a grassy meadow
Answer:
a grassy meadow
Explanation:
goo
duh
use shorthand method to represent the electrochemical reaction in a lead storage battery.
The shorthand equation shows us in a glance what happens in the electrochemical reaction. For a lead storage battery, we have; PbSO4(s)/H2O//Pb (s) ,PbO2(s) /H2SO4
What is an electrochemical reaction?An electrochemical reaction is one in which electrical energy is produced from a chemical reaction. The equations in a lead storage battery are;
Anode: Pb (s) + HSO4- → PbSO4(s) + H+ + 2 e-
Cathode: PbO2(s) + HSO4- + 3 H+ + 2 e- → PbSO4(s) + 2 H2O
Overall: Pb (s) + PbO2(s) + 2 HSO4- + 2 H+ → 2 PbSO4(s) + 2 H2O
Hence, the shorthand notation of this reaction is;
PbSO4(s)/H2O//Pb (s) ,PbO2(s) /H2SO4
Learn more about electrochemical reaction: https://brainly.com/question/7484696
What is the ph of a solution of h2so4 that has [h3o ] = 5.45 × 10–5 m? round to the nearest hundredth.
The pH of a solution of H₂SO₄ that has [H₃O⁺] is 5.45 × 10⁻⁵ M, is 4.26.
What is pH?pH is define as the negative logarithm of the concentration of H⁺ or H₃O⁺ ions, and it is represented as:
pH = -log[H⁺]
Concentration of H₃O⁺ in H₂SO₄ solution = 5.45 × 10⁻⁵ M
pH of H₂SO₄ solution will be calculated as:
pH = -log(5.45 × 10⁻⁵)
pH = -(-4.26)
pH = 4.26
Hence required pH is 4.26.
To know more about pH, visit the below link:
https://brainly.com/question/522383
Answer:
4.26 is the answer
Explanation:
edge 2022
[h+] for a solution is 2.65 x 10-2 m. this solution is a. acidic basic c. neutral
help will give brainliest
Answer:
A. acidic
Explanation:
The ksp for silver sulfate (ag2so4) is 1. 2 ✕ 10-5. Calculate the solubility of silver sulfate in each of the following
For ksp of silver sulfate (ag2so4) at 1. 2 ✕ 10-5, the solubility of silver sulfate is mathematically given as
x = 5.26*10^{-4}
What is the solubility of silver sulfate in 0.15 M AgNO3?Generally, the equation for the Chemical reaction is mathematically given as
Ag2SO4 ⇄ 2Ag+ + SO4 2-
Therefore
Ksp = [Ag+ ]2 *[SO4 2-]
1.2*10-5 = ( 0.15 +2x)2*(x)
x = 5.26*10^{-4}
In conclusion, the solubility of silver sulfate is
x = 5.26*10^{-4}
Read more about Chemical reaction
https://brainly.com/question/16416932
If the ksp of silver sulfate (ag2so4) at 1.2 × 10⁻⁵, the solubility of silver sulfate is 5.26 × 10⁽⁻⁴⁾.
What is the ksp value?ksp value determines the equilibrium between the solids and its respective ions in a solution.
The reaction is [tex]\rm Ag_2SO_4 \leftrightharpoons 2Ag+ + SO_4^2-[/tex]
The ksp pf silver sulfate is 1.2 × 10⁻⁵
Tho calculate the solubility?
Putting the values in the equation
[tex]\rm Ksp = [Ag^+ ]^2 \times [SO_4^ 2^-]\\\\1.2\times 10^-^5 = ( 0.15 +2x)2\times (x)\\x = 5.26\times 10^{-4}[/tex]
Thus, the solubility of silver sulfate is 5.26 × 10⁽⁻⁴⁾.
Learn more about silver sulfate
https://brainly.com/question/17094293
#SPJ4
A sample of solid ammonium chloride decomposes on heating
solid ammonium chloride = ammonia gas + hydrogen chloride gas
A total of 2.4 * 10^21 molecules of gas is formed
How many hydrogen atoms are present in the gaseous products
The atoms of hydrogen in the products is 2.4 * 10^21 atoms of hydrogen
What is decomposition?The term decomposition has to do with a type of reaction in which a substance is broken down into into its components.
The decomposition of ammonium chloride occurs as follows;
NH4Cl → NH3 + HCl
If 6.02 * 10^23 hydrogen atoms are present in 6.02 * 10^23 molecules
x hydrogen atoms are present in 2.4 * 10^21 molecules
x = 2.4 * 10^21 atoms of hydrogen
Learn ore about decomposition:https://brainly.com/question/8009068
#SPJ2
write the name molecular and condensed formula of alkyl groups with the following number of carbons 1,2,3,4,5,6,7,8,9,10,11,12
1)
methyl
CH3 (mol)
CH3- (struc)
2)
ethyl
C2H5
CH3-CH2-
3)
propyl
C3H7
CH3-CH2-CH2-
4)
butyl
C4H9
CH3-CH2-CH2-CH2-
5)
pentyl
C5H11
CH3-CH2-CH2-CH2-CH2-
6)
hexyl
C6H13
CH3-CH2-CH2-CH2-CH2-CH2-
7)
heptyl
C7H15
CH3-CH2-CH2-CH2-CH2-CH2-CH2-
8)
octyl
C8H17
i will stop writing the condensed formula ust add another CH2
9)
nonyl
C9H19
10)
decyl
C10H21
11)
Undecyl
C11H23
12)
dodecyl
C12H25
Find grocery items in your home look and see the product label at the back of each item identify the elements or compounds on each item use the table below for this activity grocery time 123456789 10 elements compounds
The chemical elements and compounds that are present in a grocery item such as mayonnaise include:
OilEmulsifier Vinegar SpicesSugarWhat is a product label?A product label can be defined as a paper document which contains information about the nutrients, chemical elements, and other compounds that are present in a product such as a battery, food or an edible material.
This ultimately implies that, a product label is a paper document which is used by manufactures to specify the nutrients, chemical elements, and other compounds that were used to make a particular product.
Read more on product label here: https://brainly.com/question/14446515
The ionization constant for acetic acid is 1.8 x 10-5; that for hydrocyanic acid is 4 x 10-10. in 0.1 m solutions of sodium acetate and sodium cyanide, it is true that
For the ionization constant for acetic acid is 1.8 x 10-5; that for hydrocyanic acid is 4 x 10-10, The solution is basic due to the generation of OH– ions.
What is an Ionization constant?ionization constant is simply defined as a constant that relies on the equilibrium that exists b/w ions and molecules of solution.
Generally, the equation for the Chemical reaction is mathematically given as
CH3C.O .O + H2_O ----> CH3COOH + O.H
Therefore
the anion C...N– receives H+ ion from water as it goes through hydrolysis.
Hence
xN– + H2..O ----><---- HxN + O..H–
In conclusion, The solution is basic due to the generation of OH– ions.
Read more about Chemical reaction
https://brainly.com/question/16416932
Drag each label to the correct location.
Determine whether each example represents continental drift or seafloor spreading.
oceanic ridges
concept of Pangaea
oceanic plates sliding
under continental crust
magma pushing
two plates apart
Continental Drift
Seafloor Spreading
The correct location of the given object on represents continental drift or seafloor spreading.
Continental drift: magma pushing two plates apart and concept of PangaeaSeafloor spreading: oceanic ridges and oceanic plates sliding under continental crustWhat is continental drift?The scientist Alfred Wegener is most closely connected with the concept of continental drift. Wegener wrote a paper outlining his notion that the continents were “drifting” across the Earth, occasionally crashing through oceans and into one another, in the early 20th century.
The seafloor spreading is the increase of seawater covering the land area. The spreading of seawater is decreasing the land area.
Thus, the correct location is:
Continental drift: magma pushing two plates apart and concept of PangaeaSeafloor spreading: oceanic ridges and oceanic plates sliding under continental crust.To learn more about continental drift, refer to the below link:
https://brainly.com/question/15122129
#SPJ6
why is burning not a pahse change
Answer:
This is because it is a physical change not a chemical change.
A mixture of 0.197 mol CO2 and 0.00278 mol H2O is held at 30.0 degrees celsius with a pressure of 2.50 atm. What is the partial pressure of each gas?
Considering the Dalton's partial pressure, the partial pressure of CO₂ is 2.465 atm and the partial pressure of H₂O is 0.035 atm.
Dalton's lawThe pressure exerted by a particular gas in a mixture is known as its partial pressure.
So, Dalton's law states that the total pressure of a gas mixture is equal to the sum of the pressures that each gas would exert if it were alone:
[tex]P_{T} =P_{1} +P_{2} +...+P_{n}[/tex]
where n is the amount of gases in the mixture.
Dalton's partial pressure law can also be expressed in terms of the mole fraction of the gas in the mixture. The mole fraction is a dimensionless quantity that expresses the ratio of the number of moles of a component to the number of moles of all the components present.
So in a mixture of two or more gases, the partial pressure of gas A can be expressed as:
[tex]P_{A} =x_{A} P_{T}[/tex]
Partial pressure of CO₂ and H₂OIn this case, you know:
[tex]n_{CO_{2} }[/tex]= 0.197 moles[tex]n_{H_{2}O }[/tex]= 0.00278 moles[tex]n_{T }=n_{CO_{2} }+n_{H_{2}O }[/tex]= 0.197 moles + 0.00278 moles= 0.19978 moles[tex]P_{T}= 2.50 atm[/tex]Then:
[tex]x_{CO_{2}} =\frac{n_{CO_{2}} }{n_{T} }=\frac{0.197 moles}{0.19978 moles} = 0.986[/tex][tex]x_{H_{2}O} =\frac{n_{H_{2}O} }{n_{T} }=\frac{0.00278 moles}{0.19978 moles} =0.014[/tex]Replacing in the Dalton's law:
[tex]P_{CO_{2} } =x_{CO_{2}} P_{T}[/tex]
[tex]P_{CO_{2} } =[/tex] 0.986× 2.50 atm
[tex]P_{CO_{2} } =[/tex] 2.465 atm
[tex]P_{H_{2}O } =x_{H_{2}O} P_{T}[/tex]
[tex]P_{H_{2}O } =[/tex] 0.014× 2.50 atm
[tex]P_{H_{2}O } =[/tex] 0.035 atm
Finally, the partial pressure of CO₂ is 2.465 atm and the partial pressure of H₂O is 0.035 atm.
Learn more about Dalton's partial pressure:
brainly.com/question/25181467
brainly.com/question/14119417
There are roughly 720 billion metric tons of carbon in the atmosphere. An even bigger carbon sink is found in the oceans, which contain about 40 trillion metric tons. Human activities increase the amount of carbon stored in these reservoirs. The primary source of this increase is the combustion of fossil fuels, which generates about 6 billion metric tons of carbon per year. Deforestation adds an additional 2 billion metric tons annually. Whereas 25% of this flux ends up being absorbed by the oceans and another 25% is absorbed by plants, 50% stays in the atmosphere for the duration of its residence time. How much carbon will human activities add to the atmosphere over the course of five years
A production of 17.5 × 10⁹ tonnes of carbon will be added to the atmosphere over the course of five years.
How to determine the potential carbon generation due to human activities
In accordance with the principle of mass conservation, mass is not created nor destroyed, just transformed as we infer from statement.
The total carbon generation due to human activities is the sum of the effects derived from the combustion of fossil fuels and the deforestation, whose total over the course of five years is:
[tex]x = (5\,years)\cdot \left(6\times 10^{9}\,\frac{t}{yr} + 2\times 10^{9}\,\frac{t}{yr} \right)[/tex]
[tex]x = 35\times 10^{9}\,t[/tex]
And the part of this production that will remain in the atmosphere during its residence time is:
[tex]x' = 0.5\cdot x[/tex]
[tex]x' = 17.5\times 10^{9}\,t[/tex]
A production of 17.5 × 10⁹ tonnes of carbon will be added to the atmosphere over the course of five years. [tex]\blacksquare[/tex]
To learn more on carbon dioxide, we kindly invite to check this verified question: https://brainly.com/question/3049557
zinc sulfide with oxygen has (O2) to yield zinc oxide and sulfur oxide.
(i need the formula)
Answer:
The reaction between zinc sulphide and oxygen gives zinc oxide and sulfur dioxide. The chemical equation of the reaction is: 2ZnS + 3O2 → 2ZnO + 2SO2 2 moles of ZnS react with 3 moles of O2 to form 2 moles of ZnO and 2 moles of SO2
Explanation:
Malic acid, h2c4h4o5, is a diprotic acid with ka1 = 4. 0 × 10–4 and ka2 = 6. 3 × 10–6. Calculate the ph of a 0. 50 m solution of malic acid
The pH of a 0.50M solution of malic acid with ka1 = 4. 0 × 10-⁴ and ka2 = 6. 3 × 10-⁶ as described is; 1.85.
pH of Diprotic acids: Malic AcidSince, in a polyprotic acid the first hydrogen will dissociate faster than the others, If the Ka values differ by a factor of 10-³ or more, it is possible to approximately calculate the pH by using only the Ka of the first hydrogen ion.
However, the situation is different in this scenario.
On this note, the solution is as in the attached image.
Read more on Diprotic acids;
https://brainly.com/question/26015203
The pH of a 0.50 m solution of malic acid is 1.85.
What is pH?pH is potential hydrogen. It is the measurement of the acidity and basicity of any solution.
The ka1 = 4. 0 × 10⁻⁴
The ka2 = 6. 3 × 10⁻⁶
The solution is 0.50 m.
First calculate the ka value
[tex]ka = \dfrac{x^2}{0.50} \\\\x^2 = 0.50 \times 4 \times 10^-^4\\\\x^2 = 2 \times 10^-^4\\x^2 = \sqrt{2 \times 10^-^4} \\\\ x = [H^+] = 1.41 \times 10^-^2[/tex]
Now, calculate the pH
[tex]pH = -log [H^+]\\\\pH = -log[ 1.41 \times 10^-2]\\\\pH = 1.85[/tex]
Thus, the pH of a 0.50 m solution of malic acid is 1.85.
Learn more about pH
https://brainly.com/question/15289741
#SPJ4
The pH of a 0.016-M aqueous solution of p-toluidine
(CH3C6H4NH2) is 8.60. Calculate Kb.
From the calculations performed, the Kb of the reaction is 9.9 * 10^-10
What is Kb?
The term Kb refers to the base dissociation constant of a solution. We have the following information from the question;
pH of the solution = 8.60
concentration of p-toluidine = 0.016-M
Recall that pOH = 14 - pH
pOH = 14 - 8.60 = 5.4
[OH] = Antilog (-5.4) = 3.98 * 10^-6 M
We have to set up the ICE table;
CH3C6H4NH2(aq) + H2O(l) ⇄ CH3C6H4NH3^+(aq) + OH^-(aq)
I 0.016 0 0
C -x +x +x
E 0.016 - x 3.98 * 10^-6 3.98 * 10^-6
Hence;
Kb = [3.98 * 10^-6]^2/[0.016 - 3.98 * 10^-6]
Kb = 9.9 * 10^-10
Learn more about Kb: https://brainly.com/question/12726841
Explain what the color change indicated about the changes in the concentrations of Co(H2O) 6 2+ and CoCl 4 2- in each trial?
The color of the system will change between pink and blue depending on the concentration of species.
What is equilibrium?Equilibrium is attained in a reaction when the rate of forward reaction is equal to the rate of reverse reaction. Now consider the equilibrium;
Co(H2O)6^2+(aq) + 4Cl^-(aq) ⇄ CoCl4^2-(aq) + 6H2O(l)
We know that Co(H2O)6^2+(aq) is pink while CoCl4^2-(aq) is blue hence, if the concentration of the species are changed, the color of the system will change accordingly.
Learn more about equilibrium: https://brainly.com/question/13524990?
help
Writing a Scientific Argument
Write a scientific argument that answers the question Why is the liquid oxygen machine producing less liquid oxygen than normal?
State your claim and use evidence to support it. For each piece of evidence you use, explain how the evidence supports your claim or refutes another claim. Remember to explain what happened at both the macro and molecular scales.
Answer: The liquid oxygen machine is producing less liquid oxygen than normal because there's a low attraction between the molecules.
It should be noted that oxygen in its liquid state will take up less space. It can also be stored at a lower pressure than when it's in its gaseous state.
Explanation:
From the complete question, the liquid oxygen evaporates at a slightly higher The reason for this is due to the fact that they have similarly low attraction between molecules.
What types of R groups can exist in amino acids? (Choose all that apply)
Acidic
Non-polar
Basic
Polar
Answer:
acidic,non polar,basic
Explanation:
that’s the ones I put and I got a 100% on my test just now
The types of R groups that can exist in amino acids include acidic, non-polar, basic, and polar groups.
1. Acidic R groups: These groups have a negative charge and can donate a proton (H+). An example of an amino acid with an acidic R group is aspartic acid (Asp) or glutamic acid (Glu).
2. Non-polar R groups: These groups are hydrophobic and do not have a charge. They are composed mainly of carbon and hydrogen atoms. Examples of amino acids with non-polar R groups include alanine (Ala), valine (Val), and phenylalanine (Phe).
3. Basic R groups: These groups have a positive charge and can accept a proton. An example of an amino acid with a basic R group is lysine (Lys) or arginine (Arg).
4. Polar R groups: These groups are hydrophilic and have a partial charge. They can form hydrogen bonds with other polar molecules. Examples of amino acids with polar R groups include serine (Ser), threonine (Thr), and asparagine (Asn).
Thus, types of R groups that can exist in amino acids include acidic, non-polar, basic, and polar groups.
Learn more about amino acids,here:
https://brainly.com/question/31872499
#SPJ4
In the reaction _Al 3O2→2Al2O3, what coefficient should be placed in front of the Al to balance the reaction? 1 2 3 4.
Answer:
D.) 4
Explanation:
Al + 3 O₂ --> 2 Al₂O₃
In the equation, there are:
Reactants: 1 Al and 6 O
Products: 4 Al and 6 O
To determine how many atoms there are of each, you multiply the coefficients by the subscripts attached to the atoms. While the question doesn't ask, as you can see, the oxygen atoms are balanced because there is an equal amount on both sides. To balance the aluminum atoms, you can get 4 aluminum atoms on the reactants side by using a coefficient of 4.
The new equation would look this this:
4 Al + 3 O₂ --> 2 Al₂O₃
There are now:
Reactants: 4 Al and 6 O
Products: 4 Al and 6 O