What is the atomic number?
pls help.

Answer:

See below

Explanation:

First, you need to know what a significant figure means.

The significant figures in a measurement consist of all the certain digits in one measurement, including one uncertain or estimated digit.

With that being said, the second thing we need to do is to correct the exercise. According to an external source, the exercise is the following:

a) x = 17.2 + 65.18 - 2.4

In this case, we can say that 17.2 and 2.4 has the uncertain digit at the end, but in 65.18 it's the 8. Therefore, when we make the sum of all of this we have:

x = 17.2 + 65.18 - 2.4 = 79.98

The last digit is the uncertain digit, therefore, we won't include this digit. So the final result would have 3 significant figure. However 8 surpass 5, and hence, we should approximate our result. Then our final result is:

x = 80.0

b) x = 13.0217 / 17.10

The last digit of the 13, is the uncertain. So, doing this:

x = 13.0217 / 17.10 = 0.761502924

With the correct significant figure, this would be only 4 so:

x = 0.7615

c) x = (0.0061020)*(2.0092)*(1200.00)

Applying the same principle as before:

x = (0.0061020)*(2.0092)*(1200.00) = 14.712

Hope it helps

A balanced half-reaction :

O₂(g)+ 4H⁺(aq)+ 4e⁻⇒2H₂O(l)

Given

Reduction of gaseous oxygen (O₂) to liquid water(H₂O)

Required

A balanced half-reaction

Solution

Step 1 : Equalize the number of elements by adding coefficients

Equates element O

O₂(g)⇒2H₂O(l)

Step 2 : Equalize H by adding H⁺ on the opposite side (the deficient area of H).

O₂(g)+ 4H⁺(aq)⇒2H₂O(l)

Step 3 : Equalized the charge using the addition of electrons (e⁻) along the H⁺ field.

O₂(g)+ 4H⁺(aq)+ 4e⁻⇒2H₂O(l)

Answer: Photosynthesis uses carbon dioxide, while cellular respiration produces carbon dioxide.

Explanation: i took the test lol

Answer:

Ca(OH)2 + HCI

Explanation:

Calcium hydroxides formula is: Ca(OH)2

Hydrochloric Acids formula is : HCI

Please rate and give thanks!

Answer:

i am so sorry

Explanation:

The density of copper is  If a sample 8.933 g/cm3. If copper has a volume of 12.993 cm^3. Then the mass will be 136.29 gram.

Density is defined as the mass per unit volume it means that mass present in 1 meter cube is called density. The S.I unit of density is kg/m^3 and in C.G.S it is gram/cm^3

So, In above question can understand that density, mass, and volume all are convert to each other it means that if we know any two variable then third one will be calculated easily.

Mathematically,

Formula for density will be as mentioned below:-

Density = Mass/Volume.

From above formula we can calculate mass which is as follows:-

Mass = Volume × Density.

S.I unit of mass is kilograms and C.G.S unit is gram.

So In above question

Density = 8.933 gram/cm^3

Volume = 12.993 cm^3

So from above formula

Mass = Density × volume

          = 10.49 × 12.993

          = 136.29 gram

          = 0.13629 kilogram

So Mass is equal to 136.29 gram or 0.136 kilograms.

Therefore,The density of copper is  If a sample 8.933 g/cm3. If copper has a volume of 12.993 cm^3. Then the mass will be 136.29 gram.

Learn more about density here:

https://brainly.com/question/15164682

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Answer:

4C₈H₄OH +  35O₂  →  32CO₂   +   10H₂O  

Explanation:

The unbalanced reaction expression is given as:

         C₈H₄OH +  O₂  →  CO₂   +   H₂O  

To solve this problem, we use a mathematical approach.

     aC₈H₄OH +  bO₂  →  cCO₂   +   dH₂O

Conserving C: 8a  = c

                    H:  5a  = 2d

                    O: a + 2b  = 2c + d

Let a  = 1, c  = 8, d  = [tex]\frac{5}{2}[/tex]  , b  = 35

   4C₈H₄OH +  35O₂  →  32CO₂   +   10H₂O  

Answer:

3

Explanation:

For numbers with decimals, count the number after the decimal.

Answer:

80g/mol is the molar mass of the metal

Explanation:

A divalent metal M reacts with HCl as follows:

M + 2HCl → MCl₂ + H₂

The excess of HCl is titrated with NaOH. Thus, we can solve the moles of HCl that reacts with the metal and the moles of the metal. As the atomic weight is the ratio between the mass and moles of the atom:

Moles NaOH:

0.0546L * (0.22mol / L) = 0.0120 moles NaOH = Moles HCl in excess

For NaOH and HCl solutions, Normality is the same than molarity.

Moles HCl added:

0.100L * (1.28mol / L) = 0.128 moles HCl * (50mL / 200mL) = 0.032 moles

Moles HCl in that react:

0.032 moles - 0.012 moles = 0.020 moles HCl

Moles M:

0.020 moles HCl * (1mol M / 2 mol HCl) = 0.010 moles M

Molar mass M:

0.8g / 0.010mol =

Answer:

JOSHUA

Explanation:

JOSHUA

There are 90.345 x 10^23 molecules in 15 moles of CO2.

Avogadro's number is the number of units, atoms or molecules in one mole of a substance which is equals to 6.02214076 × 1023. This number is also known as the Avogadro constant.

This means that one mole of a substance is equals to 6.02214076 × 1023 atoms, ions or molecules then 15 moles is equals to 90.345 x 10^23 molecules so we can conclude that there are 90.345 x 10^23 molecules are in 15 moles of CO2.

Learn more about mole here: brainly.com/question/1427235

Answer:

9moles of hydrogen gas

Explanation:

To solve this problem, we write the reaction expression first;

                       2H₂   +   O₂    →     2H₂O

We have been given the number of moles of oxygen gas to be:

 Number of moles of oxygen gas  = 4.5moles

From the balanced reaction expression:

      1 mole of oxygen gas reacts with 2 moles of hydrogen gas

  4.5moles of oxygen gas will react with 4.5 x 2  = 9moles of hydrogen gas

Answer:

Solar energy, wind energy, biomass energy.

Explanation:

Answer:

bro

Explanation:

guhfuyfouyvyu

Answer:

9.00

Explanation:

I took the test and got it correct ...

Answer:

Explanation:

Using the dilution formula to determine the final concentration of NaCl in the protein sample.

[tex]M_1V_1 = M_2V_2[/tex]

[tex]600 \ mM \times 1 \ mL= M_2 \times ( 1000\ mL + 1 \ mL)[/tex]

[tex]M_2= \dfrac{600 \ mM \times 1 \ mL}{ ( 1001\ mL)}[/tex]

[tex]M_2= 0.599 \ mM[/tex]

However, when dialysis attains equilibrium, it implies that the sample was dialyzed twice, SO:

[tex]M_2 = \dfrac{600 \ mM\times 1 \ mL}{201 \ mL} = 2.97 \ mM[/tex]

Now, take the concentration as 2.97 mM

Then:

[tex]M_f = \dfrac{2.985 mM \times 1 mL}{201 \ mL}[/tex]

[tex]M_f = 0.01485 \ mM[/tex]

[NaCl] = 0.01485 mM

Answer:

58.61 grams

Explanation:

Taking The molecular weight of NaCl = 58.44 grams/mole

Determine how many grams of NaCl to prepare the bath solution

first we will calculate the moles of NaCl that is contained in 6L of 170 mM of NaCI solution

= ( 6 * 170 ) / 1000

= 1020 / 1000 = 1.020 moles

next

determine how many grams of NaCl

= moles of NaCl * molar mass of NaCl

= 1.020 * 58.44

= 58.61 grams

Answer:

m = 25.98 g

Explanation:

Given data:

Density of copper metal = 8.96 g/mL

Volume of copper metal block = 2.90 mL

Mass of copper metal block = ?

Solution:

The volume of given block of copper is equal to the volume change of water by adding this block.

Density formula:

d = m/v

by putting values,

8.96 g/mL = m/ 2.90 mL

m = 8.96 g/mL × 2.90 mL

m = 25.98 g

Answer:

Hi there, the question asked is not complete but not to worry, I will give an explanation that you will be able to solve similar question or the same question when you get the whole question.

Explanation:

Oxalic acid is a diprotic acid and the acid is used with or react with sodium Hydroxide, NaOH in order to determine the molar mass of unknown diprotic acid. Oxalic Acid reacts with sodium as it is given in the balanced chemical reaction below:

(COOH)₂ + 2NaOH ------------------------------------------------------> Na₂C₂O₄ + 2H₂O.

The amount of the oxalic needed is known, say x gram and the molar mass is known. Thus, the number of moles of the oxalic acid= mass/molar mass = x gram/ 90.0 g/mol.

So we say that (COOH)₂ is a primary standard acid which is been used to standardize the base that is Sodium hydroxide.

Then, if we have an unknown diprotic acid, say H₂A, we can react it with NaOH to get the molar mass of the unknown.

H₂A + 2NaOH ---------------------------------------------------------------> Na₂A + 2H₂O.

Therefore, the number of moles of the acid = [concentration of NaOH × volume of NaOH] × [ 1 mole of the acid/ 2 mole of NaOH].

Answer:

A. Close the drying agent container whenever it is not in active use.

C. Wrap the lid of the drying agent container with tape for storage.

Explanation:

Drying agents also known as desiccants are used in pharmaceutical, food and other manufacturing to keep substances dry. These drying agents are anhydrous and hygroscopic. The right usage of these products requires that they are always stored in an air-tight container.

When they are to be removed from a container containing a solvent, they are to be separated by filtration or decanting.

Answer:

11

Explanation:

From the question given above, the following data were obtained:

Electronic configuration => 1s²2s²2p⁶3s¹

Number of electrons =?

We must understand that the electronic configuration of an element is written based the number of electrons present in the atom of the element.

To obtain the number of electrons in the atom given in the question above, we simply add up the electrons in each orbital. This can be obtained as follow:

Electronic configuration => 1s²2s²2p⁶3s¹

Number of electrons =?

Number of electrons = 2 + 2 + 6 + 1

Number of electrons = 11

Thus , the number of electrons in the atom is 11

Answer: not 100% but maybe Visable Light...sorry if thats wrong

Explanation:

Thermal energy is the another name for infrared energy.

Infrared radiation is a type of radiant energy that is  not visible to human eyes but we can feel as heat energy.

Infrared radiation (IR), also known as thermal radiation. It is that band of energy in the electromagnetic radiation spectrum with wavelengths between 780 nm and 1 mm so we can conclude that thermal energy is the another name for infrared energy.

Learn more about radiation here: https://brainly.com/question/24524460

Answer:

solar flair I think I'm not sure

Answer:

No

Explanation:

This does not mean that vinegar is insoluble totally. In fact, vinegar is soluble in water because water is a polar solvent.

For a substance to be soluble in another, it must obey the rule of solubility.

The rule states that "like dissolves like"

It implies that polar solvent will only dissolve polar solute.

Also, non-polar solvent will only dissolve non-polar solute.

Therefore, the answer is no, vinegar will dissolve in water.

Answer:

Because sugar has no ions in the solution

Explanation:

Pure water contains very few ions, so it does not conduct electricity very well. When table salt is dissolved in water, the solution conducts very well, because the solution contains ions. When sugar is dissolved in water, the solution does not conduct electricity, because there are no ions in the solution.

In basic words the more ions in the solution there is a better chance to conduct electricity.

Answer:

yes it is a chemical reaction

Explanation:

because the substances combined and made something new

Explanation:

Valence electrons is the number of electrons in the outermost shell of an atom. For the main group elements, the group number represents the number of valence electrons.

Beryllium

This belongs to the group 2 hence, it has valency of 2.

Nitrogen

This belongs to group 5, hence it has valency of 5.

Oxygen

This belongs to group 6, hence it has valency  of 6.

Fluorine

This belongs to group 7, hence it has valency of 7.

Magnesium

This belongs to group 2, hence it has valency of 2.

Phosphorus

This belongs to group 5, hence it has valency of 5

Sulphur

This belongs to group 6, it has valency of 6

Chlorine

This belongs to group 7, it has valency of 7

Answer:

Beryllium: 2 valence electrons.

Nitrogen: 5 valence electrons.

Oxygen: 6 valence electrons.

Fluorine : 7 valence electrons.

Magnesium : 2 valence electrons.

Phosphorus : 5 valence electrons.

Sulphur : 6 valence electrons.

Chlorine : 7 valence electrons.

Answer:

See explanation

Explanation:

The valence electrons are electrons found on the valence (outermost) shell of an atom.

When an atoms form compounds, there is an exchange of valence electrons between the atoms of one element and the atoms of another element.

Let us consider a typical example, sodium has one valence electron and chlorine has seven valence electrons. This means that chlorine needs one electron to complete its octet while sodium needs to release one electron in order to attain the octet structure.

So, sodium gives out its one electron and becomes a stable sodium ion and chlorine accepts that electron and becomes a stable chloride ion. This is how the compound sodium chloride is formed.

Answer:

C₁₇H₂₀N₄O₆

Explanation:

First, we need to determine the percentage of the atoms in the molecule. Then, assuming a basis of 100 we must convert the mass of each atom to moles. Simplest formula is the simplest ratio of atoms presents in the molecule:

%C:

19.88g CO2 * (12.01g/mol C / 44.01g/mol CO2) = 5.425g C

5.425g C / 10.0g * 100 = 54.25% C

%H:

4.79g H2O * (2*1.01g/mol / 18.015g/mol) = 0.537g H

0.537g H / 10.0g * 100 = 5.37%

%N:

14.89%

%O:

100 - 14.89% - 54.25% - 5.37% = 25.49%

Moles of each atom in a basis of 100g:

C: 54.25g * (1mol / 12.01g) = 4.517moles

H: 5.37g * (1mol / 1.01g) = 5.317 moles

N: 14.89g * (1mol / 14.01g) = 1.063 moles

O: 25.49g * (1mol / 16g) = 1.593 moles

Dividing each amount of moles in the lower number of moles (moles N):

C = 4.517mol / 1.063mol = 4.25

H = 5.317mol / 1.063mol = 5

N = 1.063mol / 1.063mol = 1

O = 1.593mol / 1.063mol = 1.5

This ratio multiplied 4 times to obtain whole-numbers:

C = 4.25*4 = 17

H = 5*4 = 20

N = 1*4 = 4

O = 1.5*4 = 6

The simplest formula for vitamin B6 is:

Answer:

Kindly check the picture attachment.

Explanation:

H2CO3 --------------------------> H2O + CO2

The reaction above is a decomposition reaction showing how the carbonic acid that is H2CO3 decomposed into H2O and CO2. The study of how reactants react(that is the amount in which they react) in order to form a product (and the amount of product formed) is known as the stoichiometry.

H2CO3 which is the reactant has three oxygen atoms which are all directly bonded to the carbon atom. One of the oxygen atom is bonded doubly to the carbon atom.

CO2 and H2O are the products. The CO2 is linear, O=C=O with the two oxygen atoms bonded doubly each to each carbon atoms. The H2O is bent.