The Clean Air Act legislation of 1970, 1977, and 1990 was designed to improve air quality in the United States by monitoring and reducing the emissions of air pollutants judged to pose threats to human health, such as carbon monoxide, nitrogen dioxide, sulfur dioxide, ozone, particulate matter, and lead. The main source of lead emissions in 1970 was the exhaust of vehicles burning gasoline to which tetra-ethyl lead had been added to improve combustion. By 1985, leaded gasoline was phased out of use, although airplanes and racecars were exempted. The 1990 amendments addressed the growing problem of urban smog by

Answer:

Isotopes

Explanation:

An isotope are the atoms of an element with similar chemical identity and number of protons but different atomic masses. This means that isotopes of an element differ from one another by their number of NEUTRONS.

For example, the uranium element possesses isotopes as follows: Uranium-235 and uranium-238. This two isotopes have the same chemical identity and number of protons/atomic no., which is 92. However, the atomic masses (235 and 238) are different.

Answer:

Isotopes

Explanation:

Answer:

Option a is a solution acidic ([OH⁻] = 7.0x10⁻⁹ M).

Explanation:

To know if a solution is acidic we need to calculate the pH and it must be lower than 7. A value of pH equal to 7 is a neutral solution and a solution with a pH value higher than 7 is a basic solution.

a. For the [OH⁻] = 7.0x10⁻⁹ M we have:

[tex] pOH = -log[OH^{-}] = -log(7.0 \cdot 10^{-9}) = 8.15 [/tex]

Now, the pH is:

[tex] pH + pOH = 14 [/tex]

[tex] pH = 14 - pOH = 14 - 8.15 = 5.85 [/tex]

This solution is acidic (pH < 7)

b. [H₃O⁺] = 8.5x10⁻⁸ M

[tex] pH = -log(8.5 \cdot 10^{-8}) = 7.07 [/tex]

This is not an acidic solution. Is a neutral one (pH around to 7).

c. [OH⁻] = 2.5x10⁻⁶ M

[tex] pOH = -log[OH^{-}] = -log(2.5 \cdot 10^{-6}) = 5.60 [/tex]

Then, the pH is:

[tex]pH = 14 - pOH = 14 - 5.60 = 8.40[/tex]

Hence, this is not an acidic solution. It is basic (pH > 7).    

Therefore, option a is a solution acidic ([OH⁻] = 7.0x10⁻⁹ M).

I hope it helps you!

Answer:

As water on the surface of lakes, oceans, and rivers warms up, it travels into the sky as very tiny droplets, or vapor. When the water vapor gets colder, it turns back to liquid to help form clouds.

When the liquid gets so heavy it can’t stay in the atmosphere anymore, it falls, or “precipitates,” as rain, snow, sleet, hail, or, my favorite, graupel. Once the precipitation reaches the ground or lands in lakes, oceans, and rivers, the cycle continues.

Explanation:

A scientist claims that the water molecules that you drink today could be millions of years old in the water cycle the new clouds athat re made cannot rain but the clouds which are old do rain.

The water cycle or cycle of water is the journey of each and every water molecule by which it is made up of as the clouds in the environment are made up of the evaporation process in the environment.

The vapors of evaporation condense in the environment to form the clouds and these clouds are only responsible for the rain but the old and heavy clouds can only do it.

Therefore, in the water cycle, the new clouds are made cannot rain but the clouds which are old do rain scientist claim that the water molecules that you drink today could be millions of years old.

Learn more about the water cycle, here;

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#SPJ2

Answer:

e.

6.7

hope it help

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Answer:

chemical reaction between those a b c it's a reaction which occurs when heating

Explanation:

your answer was correct

Answer:

Explanation:

Potassium (K) atom has 19 electrons. The full electron configuration of Potassium (K) is 1s22s22p63s23p64s1

Principal energy level

Quantum number: n

1

2

3

4

5

6

Sublevels

availableQuantum number: l

1s

2s 2p

3s 3p 3d

4s 4p 4d 4f

5s 5p 5d 5f 5g

6s 6p 6d 6f 6g 6h

Answer:

Chlorine

Explanation:

the ionization increases as you get closer to the top right. since chlorine (Cl) is the only one of the answer choices that is closer to the top right corner compared to phosphorous (P), that is the answer.

Answer:

cl

Explanation:

because ionization energy decrease from left to right

Answer:

1)Or

d.Sublimation

2)

b.iodine is the solute and alcohol is solvent

3)

a.compostion of solute

Answer:

1) a) centrifugation

OR

b) sublimation

2) a) iodine is the solute and alcohol is solvent

3) a) concentration of soLute

ANSWER

2Ba + 2HBr → 2BaBr + H2

2BiCl3 + 3H2S → Bi2S3 + 6HCl

Br2 + 2KI → I2 + 2KBr

4Fe + 3O2 → 2Fe2O3

Answer:

[tex]3Mg _{(s)} + N _{2(g)} → Mg_{3} N _{2(s)}[/tex]

[tex]Ba _{(s)} + 2HBr_{(g)} → BaBr _{2(s)} + H _{2(g)}[/tex]

[tex]2BiCl_{3(s)} + 3H_{2} S _{(g)} → Bi _{2} S _{ 3(g)} + 6HCl _{(g)} \\ [/tex]

[tex]Br_{2(g)} + 2KI _{(g)} → I _{2(g)} +2 KBr _{(g)}[/tex]

[tex]4Fe_{(s)}+ 3O_{2(g)} → 2Fe_{2} O _{3(s)} [/tex]

when ph decrease that means acidity increase

when ph increase that means basicity increase

Answer:

Cytoplasm is a thick solution that fills each cell and is enclosed by the cell membrane. It is mainly composed of water, salts, and proteins. All of the organelles in eukaryotic cells, such as the nucleus, endoplasmic reticulum, and mitochondria, are located in the cytoplasm.

Answer:

Explanation:

                             Cytoplasm is a thick solution that fills each cell and is enclosed by the cell membrane. It is mainly composed of water, salts, and proteins. All of the organelles in eukaryotic cells, such as the nucleus, endoplasmic reticulum, and mitochondria, are located in the cytoplasm. ...

Answer:

All systems will exchange matter and energy with their surroundings.

Explanation:

Answer:c

Explanation:

Are you ready kids?

Aye, aye Captain.

I can't hear you!

AYE, AYE CAPTAIN!

Oooooooooh.

Who lives in a pineapple under the sea?

Spongebob squarepants!

Absorbent and yellow and porous is he?

Spongebob squarepants!

If nautical nonsense be something you wish!

Spongebob squarepants!

Then drop on the deck and flop like a fish!

Spongebob squarepants!

Ready?

Spongebob squarepants.

Spongebob squarepants.

Spongebob squarepants.

Spongebob squarepants.

Spongebob-squarepants.

1st part is ure answer --> 2M

Given mass -> 58 grams

mass of NaCl -> 58.44 approx -> 58 any

moles given-> 1 moles

[tex]Molarity = \frac{moles}{vol \: in \: lts} [/tex]

[tex]Molarity = \frac{1}{0.5} = \frac{10}{5} \\Molarity = 2M[/tex]

Answer:

Pour the sugar/diamond mixture into a container of water and stir until the sugar is dissolved completely. Then strain the mixture and wash the diamonds with water.

Answer:

Stir with a large enough volume of cold water to dissolve all the sugar. Filter to leave the diamonds on the filter paper. Wash on the filter paper with more water to remove any last traces of sugar solution. Allow to dry.

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Answer:

second (S) is the SI unit of time.

Answer:

second

Explanation:

the gap between any two intervals is called time

time can be measured in hour,minute,second

but second is the SI unit of time

Answer:

nNaOH = 0,2 mol

Trong hỗn hợp các chất đề bài cho chỉ có phenol tác dụng với NaOH

C6H5OH + NaOH → C6H5ONa + H2O

   0,2  ←     0,2 (mol)

⟹ mphenol = 0,2.94 = 18,8 gam

⟹  

%mC6H5OH=18,8/28,9 x100%= 65,05%

Explanation:

Answer:

Be,Mg,Ra etc

Explanation:

It should be palced in group 2A because as it reacts with chlorine in ratio of 1:2 . It's valancy is 2 and is metal as it react with non metal donating two electrons .

one more thing it fits there orderly

answer is wildlife sanctuary

Answer:

a wildlife sanctuary

Explanation:

In this problem, we need to find the pH of a buffer (pH = 4.45) that is produced by the reaction of strong acids as HBr that reacts with weak bases as NaC₇H₅O₂ producing its weak acid and a salt, as follows:

HBr + NaC₇H₅O₂ → HC₇H₅O₂ + NaBr

If in the reaction, the limiting reactant is the strong acid, we will produce a buffer (The aqueous mixture of a weak acid and its strong base).

Using Henderson-Hasselbalch equation, we can find the pH of this buffer:

[tex]pH = pKa + log \frac{[NaC_7H_5O_2]}{[HC_7H_5O_2]}[/tex]

Where:

pKa is -log Ka = 4.20

[] could be taken as the moles of each species

After the reaction, the moles of HBr = Moles of HC₇H₅O₂ and the remaining moles of NaC₇H₅O₂ = Initial moles of NaC₇H₅O₂ - Moles of HBr.

Moles HBr:

22.5mL = 0.0225L * (0.200mol/L) = 4.5x10⁻³ moles HBr

Moles NaC₇H₅O₂:

50.0mL = 0.0500L * (0.250mol/L) = 0.0125 moles NaC₇H₅O₂

That means the moles after the reaction of the species of the buffer are:

Moles HC₇H₅O₂ = Moles HBr = 4.5x10⁻³ moles

Moles NaC₇H₅O₂ = 0.0125 moles - 4.5x10⁻³ moles = 8.0x10⁻³ moles

Replacing in H-H equation:

[tex]pH = 4.20+ log \frac{[8.0x10^{-3}]}{[4.5x10^{-3}]}[/tex]

pH = 4.45

Learn more about Henderson-Hasselbalch equation in:

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Answer:

light

Explanation:

Have a nice day

Answer:

light

Explanation:

Answer:

4.48×10⁶ dm³

Explanation:

We'll begin by converting 23.4 tonnes to grams (g). This can be obtained as follow:

1 tonne = 10⁶ g

Therefore,

23.4 tonnes = 23.4 × 10⁶

23.4 tonnes = 2.34×10⁷ g

Thus, 23.4 tonnes is equivalent to 2.34×10⁷ g

Next, we shall determine the number of mole in 2.34×10⁷ g of NaCl. This can be obtained as follow:

Mass NaCl = 2.34×10⁷ g

Molar mass of NaCl = 58.5 g/mol

Mole of NaCl =?

Mole = mass / molar mass

Mole of NaCl = 2.34×10⁷ / 58.5

Mole of NaCl = 4×10⁵ moles

Next, we shall determine the number of mole of chlorine, Cl₂ produced from the reaction. This can be obtained as follow:

2NaCl —> 2Na + Cl₂

From the balanced equation above,

2 moles of NaCl reacted to produce 1 mole of Cl₂.

Therefore, 4×10⁵ moles of NaCl will react to produce = (4×10⁵ × 1)/2 = 2×10⁵ moles of Cl₂.

Thus, 2×10⁵ moles of Cl₂ were obtained from the reaction.

Finally, we shall determine the volume of Cl₂ produced. This can be obtained as follow:

1 mole of Cl₂ at stp = 22.4 dm³

Therefore,

2×10⁵ moles of Cl₂ at stp = 2×10⁵ 22.4

2×10⁵ moles of Cl₂ at stp = 4.48×10⁶ dm³

Thus, the volume of chlorine obtained from the reaction is 4.48×10⁶ dm³

What is wrong with the experimental design is that the student changed more than one independent variable.

WHAT AN EXPERIMENT SHOULD CONTAIN?

In the experiment conducted by the student in this question in order to determine how the temperature of water affects the time for sugar to dissolve. The independent variable is the DIFFERENT TEMPERATURE OF WATER while the dependent variable is the TIME TAKEN FOR SUGAR TO DISSOLVE.

N.B: An experiment should have only one independent variable and all other variables should be kept constant. This is to have a reliable result.

Therefore, the fact that the student changed more than one independent variable is wrong for the experimental design.

Learn more: https://brainly.com/question/967776

Answer:

The student changed too many variables.

Explanation:

in k-12 took the quiz

Answer: In ionic bonding (a noble gas configuration is formed for each element or ion).

Explanation:

IONIC bonding, which is also called electrovalent bonding involves the complete transfer of electrons from one atom to another in order to attain a noble gas electron configuration.

The noble gases or group 0 elements have a completely filled outermost shell of eight electrons. This makes them generally very stable, that is, unreactive. There is a natural drive for other atoms to attain the electron configuration of group 0 (inert gases) elements. This usually results in atoms entering into chemical combinations by losing, gaining or sharing electrons.

Ionia compound such as sodium chloride

--> have high melting points because alot of heat energy is required to break the attractive forces between the ions;

--> are hard and brittle;

--> are soluble in water;

--> conduct electricity when in solution or molten form because the ions are able to move about, that is, they are electrolytes

Answer:

C.

Explanation:

Answer A is incorrect because a compound doesn't have to be made with only metals.

Answer B is incorrect because that is actually the definition of a pure element.

Answer C is correct because to make a compound, there has to be a chemical reaction where bonds are formed and an entirely new substance is created.

Answer D is incorrect because compounds cannot be separated by physical means.

Hope this helps :D

Explanation:

For example, elephants form groups with only females and their offspring. Once the male offspring reach a certain age, they leave the group and become solitary. Which is a benefit of this type of social group structure? A:Females do not have to compete for a mate.

Answer:

- 10.6° C

Explanation:

Given that,

In the aqueous sucrose solution,

Molality of the solution (m) = 5.7

Freezing point constant (K) = 1.86

To find,

The freezing point of the solution = ?

Method:

To find its freezing point, we will first find out if the solute demonstrates an electrolyte or not.

In case it is not, the van't Hoff factor i.e. ration of particles' concentration denoted by (i) would be taken as 1. So,

ΔT(change in temperature) = i * m * K              (putting the given values)

= 1 * 5.7 * 1.86

= 10.6° C

Thus, the freezing point equals to 0 - 10.6° C = -10.6° C.