1. What was the first recorded element to be discovered?

Answer:

carbon-12

Explanation:

carbon 6/12 isotope has 6 neutrones and it is considered as a metal.

Answer:

no

Explanation:

no, because food has unhealthy products now especially from fast foods they add chemicals.

Answer:

3 sulphur is more electrically –

1. ₉¹⁹F

2. Mg(OH)₂

3. 2H₂ + O₂ ⇒ 2H₂O

1. Fluorine, atomic number : 9 , mass number = 19

Symbol : ₉¹⁹F

protons=electrons=atomic number = 9

neutrons = mass number - atomic mass

[tex]\tt n=19-9=10[/tex]

Configuration : [He] 2s² 2p⁵

2. Magnesium hydroxide is an ionic compound and is a strong base consisting of 2 ions:

Positive ion: Magnesium: Mg²⁺

negative ion: Hydroxide: OH⁻

The charges of the two are crossed, so that the compound becomes:

Mg(OH)₂

3. Reaction :

H₂ + O₂ --------> H₂O

give coefficient :

aH₂ + bO₂ --------> H₂O

H, left = 2a, right 2⇒2a=2⇒a=1

O, left = 2b, right 1⇒2b=1⇒b=0.5

Reaction becomes :

H₂ + 0.5O₂ --------> H₂O x 2

2H₂ + O₂ --------> 2H₂O

Answer: Iconic

Explanation:Ionic bonds are formed through the exchange of valence electrons between atoms, typically a metal and a nonmetal.

Answer:

The newspaper article's statement is correct since the mass of CO₂ reduced = 1071.85 pounds

Explanation:

Equation for the combustion of gasoline (octane) is given below:

2C₈H₁₈ + 25O₂ ---->  16CO₂ + 18H₂O

Density of C₈H₁₈ = 0.8 g/mL

Assuming mileage of the car is 20 miles/gallon; 1 gallon = 3.785 L

Since 20 miles is reduced in driving each week, thereby saving 1 gallon of gasoline, number of litres of gasoline reduced in a year is given by;

52 * 3.785 L = 196.82 L = 196820 mL

density = mass/volume; mass = density * volume

mass of gasoline saved = 0.8 g/mL * 196820 mL = 157456 g

number of moles = mass/molar mass

Molar mass of C₈H₁₈ = 114  g/mol

number of moles of C₈H₁₈ in 157456 g = 157456 g / 114 g/mol = 1381.2 moles

From the equation of reaction, 2 moles of C₈H₁₈ produces 16 moles of CO₂

1381.2 moles of C₈H₁₈ will produce 1381.2 * 16/2 moles of CO₂ = 11049.6 moles of CO₂

mass = number of moles * molar mass

molar mass of CO₂ = 44 g/mol

mass of CO₂ = 11049.6 moles * 44 g/mol = 486182.4 g

1 g = 0.00220462 pounds

Therefore mass of CO₂ reduced = 486182.4 g * 0.00220462 lb/g

mass of CO₂ reduced = 1071.85 pounds

Therefore, the newspaper article's statement is correct

Answer:a negative charge

Explanation:

while an atom that gains electrons and becomes negatively charged is known as an anion.

Answer:

Once you have identified the limiting reactant, you calculate how much of the other reactant it must have reacted with and subtract from the original amount.

Explanation:

 1.  Write the chemical equation.

   2.Calculate the moles of product from the first reactant.

   3.Calculate the moles of product from the second reactant.

   4.Identify the limiting reactant and the excess reactant.

   5.Calculate the mass of excess reactant used up.

   6.Calculate the mass of unused excess reactant.

   7.Calculate the mass of limiting reactant needed to react with the unused excess reactant.

Answer:

P₂ = 5000 KPa

Explanation:

Given data:

Initial volume = 2.00 L

Initial pressure = 50.0 KPa

Final volume = 20.0 mL (20/1000=0.02 L)

Final pressure = ?

Solution:

The given problem will be solved through the Boly's law,

"The volume of given amount of gas is inversely proportional to its pressure by keeping the temperature and number of moles constant"

Mathematical expression:

P₁V₁ = P₂V₂

P₁ = Initial pressure

V₁ = initial volume

P₂ = final pressure

V₂ = final volume  

Now we will put the values in formula,

P₁V₁ = P₂V₂

50.0 KPa × 2.00L = P₂ × 0.02 L

P₂ = 100 KPa. L/0.02 L

P₂ = 5000 KPa

Answer:

D

Explanation:

[tex]4 \times - 176 = - 704[/tex]

Answer:

D - 704

Explanation:

The balanced thermochemical equation relates the energy change to moles, not grams, so we first convert the amount of NH4Ck to moles and then use the thermochemical equation to determine the energy change:

4.00 mole NH4Cl x (-176 ÷ 1 mole NH4Cl)

= -704

Answer:

I found this in an article "There is frequently the odor of sulfur. This is due to a reaction between traces of iron in the yolk and sulfur in the white. It happens only when the eggs have been overcooked. Perfectly cooked yolks are moist and deep orange."

Explanation:

Hope that helps

Answer:

Dipole-dipole forces

Explanation:

A polar compound is that compound which contains atoms that have a difference in charges i.e electrostatic attraction occurs between its constituent atoms. Polar molecules are attracted to other polar molecules with opposite charges and her held together with the aid of certain forces

The attractive force between the negative part of a polar molecule (-) and the positive part of another polar molecule (+) is called DIPOLE-DIPOLE FORCES. This dipole-dipole force gets stronger with an increasing polarity of the molecules involved.

Answer:

it is number 2

Explanation:

hope this helps it is number 11

Answer: They Have Waxy Leaves And Stems

Explanation:

:)

Answer:

have waxy leaves and stems

&

produce seeds quickly

Hope this helps good luck :)

Answer:

In acid – base chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. Basic salts contain the conjugate base of a weak acid, so when they dissolve in water, they react with water to yield a solution with pH greater than 7.0.

Explanation:

Hope this helped!

Answer:

People just don't really seem to care about how much smog is being polluted anymore.  So they still continue to go over the limit of smog and smoke that is supposed to be produced, which cause harm and damage to the environment around us. Hope this helps!

Explanation:

Answer:

U

Explanation:

UUUUUUUUUUUUUU

Answer:

silver

Explanation:

The most electrically conductive element is silver, followed by copper and gold. Silver also has the highest thermal conductivity of any element and the highest light reflectance.

Answer:

A. copper

Explanation:

edge 2021

Answer:

The number of degrees of longitude that separates New York City from Denver, Colorado is 30.9843 degrees longitude

Explanation:

The longitude of New York City is 74.0060° W

The latitude of New York City is 40.7128° N

The longitude of Denver, Colorado is 104.9903°W

The latitude of Denver Colorado is 39.7392°N

Therefore, the difference the number of degrees of longitude that separates New York City from Denver, Colorado is 104.9903 - 74.0060 = 30.9843°.

Answer:

as soon as the pollen reaches the stigma after the pollen grain descends down the style when the pollen tube grows into the ovule when the seed germinates

Explanation:

Answer:

for its one mole it is of 28gram. according to mole concept in one mole, there is 6.022*10^23 moles are present. so mass of 1 molecule of nitogen gas is 28/(6.022*10^23)

The mass of calcium sulfite produced : 15 g

A reaction coefficient is a number in the chemical formula of a substance involved in the reaction equation. The reaction coefficient is useful for equalizing reagents and products.

Reaction

CaO + SO₂ → CaSO₃

mol CaO (MW=56 g/mol)

[tex]\tt \dfrac{7}{56}=0.125[/tex]

Because sulfur dioxide is an excess, so mol CaSO₃ based on mol CaO

From the equation, mol ratio of mol CaSO₃ : mol CaO=1 : 1, so mol CaSO₃ :

[tex]\tt \dfrac{1}{1}\times 0.125=0.125[/tex]

mass CaSO₃ (MW=120 g/mol) :

[tex]\tt 0.125\times 120=15~g[/tex]

Answer:

Mass = 5.33 g

Explanation:

Given data:

Mass of Al = 2.80 g

Mass of Cl₂ = 4.15 g

Theoretical yield of AlCl₃ = ?

Solution:

Chemical equation:

2Al  +  3Cl₂        →       2AlCl₃

Number of moles of Al:

Number of moles = mass/molar mass

Number of moles = 2.80 g/ 27 g/mol

Number of moles = 0.10 mol

Number of moles of Cl₂:

Number of moles = mass/molar mass

Number of moles = 4.15 g/71 g/mol

Number of moles = 0.06 mol

Now we will compare the moles of AlCl₃ with Al and Cl₂.

                    Cl₂           :        AlCl₃

                    3              :          2

                   0.06         :        2/3×0.06 = 0.04

                   Al             :        AlCl₃

                     2            :          2

                   0.10         :        0.10

Number of moles of AlCl₃ produced by chlorine are less so it will be limiting reactant.

Mass of AlCl₃:Theoretical yield

Mass = number of moles ×molar mass

Mass = 0.04 mol × 133.34 g/mol

Mass = 5.33 g

5.33 grams is the theoretical yield of AlCl₃ in this reaction.

Theoretical yield of any reaction tells about the accurate quantity of the product formed by the complete consumption of reactants.

Given chemical reaction is:

2Al + 3Cl₂ → 2AlCl₃

First we convert the mass of reactants into moles by using the formulas:

n = W/M, where

W = given mass

M = molar mass

Given mass of Al = 2.80 g

Moles of Al = 2.80/27 = 0.10 mole

Given mass of Cl₂ = 4.15 g

Moles of Cl₂ = 4.15/71 = 0.06 mole

From this calculation we conclude that Cl₂ is the limiting reagent, so the formation of product depends on Cl₂.

From the stoichiometry of the reaction, it is clear that:

3 moles of Cl₂ = produce 2 moles of AlCl₃

0.06 moles of Cl₂ = produce 2/3×0.06 = 0.04 moles of AlCl₃

Now we calculate the produced mass of AlCl₃ as:

W = 0.04mol × 133.34g/mol = 5.33g

Hence, 5.33g is the produced theoretical yield.

To know more about Theoretical yield, visit the below link:

https://brainly.com/question/21091465

Answer:

Since the replication crisis, many practices have been implemented to improve research and promote open science, or the practice of sharing data and materials so they can be reviewed and replicated by other researchers. One of these practices involves submitting the proposed methods and analysis plan to journals in advance for approval or preregistration. This practice allows scientific journals to approve experiments before they are done, with the guarantee that any finding will be published regardless of whether or not it is significant. This process also prevents researchers from harking, or creating theories or hypotheses that explain the results of a study after the data has been collected.

Explanation:

The blanks in the text above were filled with the terms that best fit the context and meaning of the message that the text, in general, wanted to convey. No grammatical element and no punctuation has been modified, which allows the text to maintain its original coherence and meaning.

The added terms are in agreement with the scientific denominations currently accepted.

Answer: Exosphere

Explanation: Exosphere. This is the outermost layer of the atmosphere. It extends from the top of the thermosphere to 6,200 miles (10,000 km ) above the earth.

the exosphere is the outermost layer of the atmosphere

Explanation:

Matter can be classified into two broad categories: pure substances and mixtures. ... A material composed of two or more substances is a mixture. Elements and compounds are both examples of pure substances. A substance that cannot be broken down into chemically simpler components is an elementOne useful way of organizing our understanding of matter is to think of a hierarchy that extends down from the most general and complex to the simplest and most fundamental (Figure 3.4.1 ). Matter can be classified into two broad categories: pure substances and mixtures. A pure substance is a form of matter that has a constant composition (meaning that it is the same everywhere) and properties that are constant throughout the sample (meaning that there is only one set of properties such as melting point, color, boiling point, etc. throughout the matter). A material composed of two or more substances is a mixture. Elements and compounds are both examples of pure substances. A substance that cannot be broken down into chemically simpler components is an element. Aluminum, which is used in soda cans, is an element. A substance that can be broken down into chemically simpler components (because it has more than one element) is a compound. For example, water is a compound composed of the elements hydrogen and oxygen. Today, there are about 118 elements in the known universe. In contrast, scientists have identified tens of millions of different compounds to date.

An element is a substance which can be split into simpler unit by ordinary chemical prcess.

Compound this is a pure substance that is composed of two or more element in a fixed and definite portion.

Mixture contains two or more constituents which can be easily separated by physical method.

Answer:

41.25g

Explanation:

Given parameters:

Half-life of Technetium - 104  = 18minutes

Mass = 165g

Unknown:

Mass of sample remaining after 36minutes = ?

Solution:

The half-life of a radioactive element is the time taken for half of the element to decay;

Now;

                Start           First half life              Second half-life

Time          0                      18min                        36min

 Mass       165g                 82.5g                        41.25g