Consider the following reaction:
Mg + 2H2O Mg(OH)2 + H2 ΔH = -353 kJ

This reaction is
A.
exothermic because heat is released.
B.
endothermic because heat is released.
C.
endothermic because heat is absorbed.
D.
exothermic because heat is absorbed.

Answer:

cellular respiration

Explanation:

hope this helps :)

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Answer:

In the picture A kettle is boiling water and evaporating it we can see the water vapours coming out of the kettle and there is a paper on top of the kettle from where the water vapours are coming out .

Explanation:

is this right ?? i hope it helps

Answer:

a hydrogen atom contains only one proton in it's nucleus, while atoms of all other elements contain more than one proton

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Answer:

O it's not

Explanation:

Have a great day!

It requires 60 mL of 0.20 M sodium hydroxide [tex](NaOH)[/tex] to neutralize 25 mL of carbonic acid [tex](H_2CO_3)[/tex], hence the carbonate ions concentration is [tex]0.24M[/tex].

Given:

Reaction:

[tex]\to \bold{2NaOH + H_2CO_3 \to Na_2CO_3 + 2H_20 }[/tex]

[tex]NaOH[/tex] volume [tex](V_B) = 60 \ ml[/tex]  

[tex]H_2CO_3[/tex] Volume [tex](V_A) = 25\ ml[/tex]  

[tex]NaOH[/tex] Molarity [tex](C_B) = 0.20\ M[/tex]

[tex]H_2CO_3[/tex] moles [tex](n_A) = 1[/tex]

[tex]NaOH[/tex] moles [tex](n_B) = 2[/tex]

To find:

[tex]H_2CO_3[/tex] Molarity [tex](C_A) =?[/tex]

Solution:

Using the neutralization reaction:  

[tex]\to \frac{C_AV_A}{C_BV_B} =\frac{n_A}{n_B} \\\\[/tex]

[tex]\to C_B = 0.2\ M \\\\ \to n_A = 1 \\\\ \to n_B = 2 \\\\ \to V_B = 60\ ml \\\\ \to V_A = 25\ ml[/tex]

Calculating the [tex]C_A[/tex]:

 [tex]\to \frac{C_A \times 25}{0.2 \times 60} =\frac{1}{2} \\\\\to C_A =\frac{1 \times 0.2 \times 60}{2 \times 25} \\\\\to C_A =\frac{1 \times 2 \times 12}{2 \times 5 \times 10} \\\\ \to C_A =\frac{ 12}{ 5 \times 10} \\\\\to C_A = \frac{6}{5 \times 5} \\\\\to C_A = \frac{6}{25} \\\\\to C_A=0.24\ M[/tex]

Therefore, the concentration of carbonic acid is "0.24M".

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The concentration of carbonic acid( H₂CO₃) is 0.24 M.

The given reaction:

2 NaOH + H₂CO₃ → Na₂CO₃ + 2H₂O

Volume of NaOH  = 60mL

Volume of H₂CO₃ = 25 mL

Molarity of NaOH= 0.20M

To find:

Molarity of H₂CO₃=?

2 moles of NaOH and 1 mol of H₂CO₃ reacts to give 1 mol of Na₂CO₃.

Using the neutralization reaction:  

Consider A to be NaOH and B to be  H₂CO₃

[tex]\frac{\text{Number of moles of A}}{\text{Number of moles of B}} =\frac{\text{Molarity of A*Volume of A}}{\text{Molarity of B*Volume of B}}[/tex]

On substituting the values in order to calculate molarity of H₂CO₃:

[tex]\text{Molarity of B}=\frac{1*0.2*60}{2*25} \\\\\text{Molarity of B}=0.24M[/tex]

Therefore, the concentration of H₂CO₃ is 0.24 M.

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Answer:

[tex]FeCl_{2} +H_{2} S->FeS + 2HCl[/tex]

Explanation:

I am assuming that we have to balance this equation. On the left side, we have one Fe, 2 H, 2 Cl, and 1 S. On the right side, we have 1 Fe, 1 H, 1 Cl, and 1 S. Adding a 2 as a coefficient in front of the HCl on the right side will make 2 H and 2 Cl instead, balancing the overall equation.

FeCl_{2} +H_{2} S- > FeS + 2HClFeCl 2 +H 2 S−>FeS+2HCl

Answer:

5 significant figures

Explanation:

The zeros as considered when they are in between or after numbers greater than zero.

Ex1: 0.005 = 1 significant figure

Ex2: 0.0050 = 2 significant figure

Ex3: 0.05500= 4 significant figure

Ex4: 5.00 = 1 significant figure

Answer:

pl

saponification palmitate

Answer:

1. The kinetic energies of the particles (atoms, molecules, or ions) that make up a substance. Kinetic energy tends to keep the particles moving apart.

2. The attractive intermolecular forces between particles that tend to draw the particles together.

Answer:

Cl2(g) + 2 NaOH(aq) = NaCl(aq) + NaClO(aq) + H2O(l)  

Explanation:

The enthalpy of this reaction is -5315 KJ/mol.

The equation of the reaction is;

2C4H10(g) + 13O2(g) -----> 8CO2 (g) + 10H2O(g)

We know that the enthalpy of reaction can be obtained from the enthalpy of formation of the reactants and products as follows;

ΔHrxn = ΔHf(products) - ΔHf(reactants)

We have the following information from the question;

ΔHf C4H10 = - 125. 6 kJ/mol

ΔHf CO2 = - 393. 5 kJ/mol

ΔHf H2O = - 241. 82 kJ/mol

ΔHf O2 = 0 KJ/mol

Hence;

[(8 × (- 393. 5 )) + (10 × (-  241. 82))] - [2( - 125. 6))]

= -5315 KJ/mol

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Answer:

nitrogen have more protons per atom than phosphorus

Oxygen and fluorine are the two elements that have more protons per atom than the element phosphorus.

Phosphorus (P), a nonmetallic chemical element of something like the nitrogen group (Group 15 [Va] of the periodic table), is a colorless, semitransparent, soft, sticky solid that glows in the dark at room temperature.

Hennig Brand, a German businessman with an interest in alchemy, appears to have discovered phosphorus around 1669. Brand left 50 buckets of pee alone till they putrified and "produced worms." He then reduced the urine to a paste and burned it with sand to extract elemental phosphorus first from combination.  Oxygen and fluorine are the two elements that have more protons per atom than phosphorus.

Therefore, oxygen and fluorine are the two elements that have more protons per atom than phosphorus.

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Answer:

Light from the window reflecting off the face of his watch <33

Answer:

20g

Explanation:

hope helpful.............

Answer:

4 meters

Explanation:

4 centimeters and millimeters are too small, while 4 kilometers is too large.

Answer:

i belive the answer you are looking for is A.. hope this helps!

Explanation:

im not really 100% certain of this answer due to the fact i am a little rusty.

Molecules are formed when two or more atoms chemically bond together. In 3H₂(SO)₄, three molecules are present.

Molecules are the smallest unit present in any compound and are formed by a group of atoms. A number denoted in front of the chemical species is the coefficient that represents the number of molecules.

The coefficient present in front of the reactant or the product in a chemical reaction gives the number of the molecules present in a compound. As three is denoted in front of the sulphuric acid, hence will be the number of the molecules.

Therefore, there are three molecules present in sulphuric acid.

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Answer:

B a shared pair of electrons (2)

Explanation:

In Lewis structures, a single line represents a single pair of electrons. This means that the elements share 2 electrons or one pair of electrons

Hope this helps!

The shared electrons behave as if they belong to both atoms in the bond and bind the two atoms together to form a molecule. The shared electrons are typically depicted as a line (—) connecting the bonded atoms. (A line in a Lewis structure represents two electrons. Therefore, option A is correct.

Lewis structures, also known as Lewis dot formulas, Lewis dot structures, electron dot structures, or Lewis electron dot structures, are diagrams that depict the bonding between atoms in a molecule as well as any lone pairs of electrons that may exist.

A Lewis structure is based on the octet rule, which states that atoms share electrons in order for each atom to have eight electrons in its outer shell. An oxygen atom, for example, has six electrons in its outer shell.

Gilbert N. Lewis, who introduced the Lewis structure in his 1916 article The Atom and the Molecule, was named after it. Lewis structures expand on the electron dot diagram concept by adding lines between atoms to represent shared pairs.

Thus, option A is correct.

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When perfume or cologne is sprayed into the air, it turns into a gas and its particles mix with other air particles that quickly move around the room. This is because gas is the least dense of the three states of matter. It moves quickly into any space or volume because it has the least density. This is called diffusion, when molecules or particles move from areas with high concentration to low concentration areas. 

Answer:

0.1 M

Explanation:

(25 mL) (0.20 M) / 50 mL = 0.1 M

Answer:

160.3 g S

Explanation:

Answer: the answer is  b

Explanation:I took the test and got it

pls mark as brainliest if correct for you

The statement is true in this situation is C. The size of Ffric is the same as the size of Fapp:

From the diagram, since the body is in equilibrium, the sum of vertical forces equals zero. Also, the sum of horizontal forces equal zero.

So, ∑Fx = 0 and ∑Fy = 0

Since Fapp acts in the negative x - direction and Ffric acts in the positive x - direction,

∑Fx = -Fapp + Ffric = 0

-Fapp + Ffric = 0

Fapp = Ffric

Also, since Fgrav acts in the negative y - direction and Fnorm acts in the positive y - direction,

∑Fy = Fnorm + (-Fgrav) = 0

Fnorm - Fgrav = 0

Fnorm = Fgrav

So, we see that the size of Fapp equals size of Ffric and the size of Fnorm equals the size of Fgrav.

So, the correct option is C

The statement which is true in this situation is C. The size of Ffric is the same as the size of Fapp.

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Answer:

Ok the poprtion would look like this :  x                   23  

                                                          -----------   =     ----------

                                                            230                 100

Explanation:

So for the last fill in it could be 52.9 or 60

i hope i got it correct lol pretty sure i did

Answer:

we do the best possible in our

Answer:

Speed =d/t. 200÷10=21÷1000=0.021 km/h

Explanation:

S=D/T

a.

The atomic radius of iridium is 1.355 Å

For a face-centered cubic unit cell, with edge length, a and atomic radius r,

we have a² + a² = (4r)²

2a² = 16r²

r² = a²/8

r = a/√8

Since a = 3.833 Å,

Substituting this into the equation, we have

r = a/√8

r = 3.833 Å/√8

r = 3.833 Å/2.828

r = 1.355 Å

So, the atomic radius of iridium is 1.355 Å

b.

The density of iridium metal is 22.67 g/cm³

To find the density of the iridium metal, we need to find the mass of atoms per unit cell.

So, for the face centered cubic iridium atom, there are 6 faces per unit cell × 1/2 atoms per face + 4 corners per unit cell × 1/4 atoms per corner = 3 atoms + 1 atom = 4 atoms per unit cell.

So, the mass of the atoms in the unit cell is m = number of atoms/cell × number of moles/atom × molar mass of Iridium

= 4 atoms/cell × 1 mol/6.022 × 10²³ atoms × 192.22 g/mol

= 768.88/6.022 × 10²³ g/cell

= 127.68 × 10⁻²³ g/cell

= 1.2768 × 10⁻²¹ g/cell

Next, we need to find the volume of the unit cell which is V = a³

= (3.833 Å)³

= (3.833 × 10⁻¹⁰ m)³

= 56.314 × 10⁻³⁰ m

= 5.6314 × 10⁻²⁹ m

So, the density of iridium = mass of unit cell/volume of unit cell

= m/V

= 1.2768 × 10⁻²¹ g/cell ÷ 5.6314 × 10⁻²⁹ m

= 0.2267 × 10⁸ g/m³

= 0.2267 × 10⁸ g/m³ × 10⁻⁶ m³/cm³

= 0.2267 × 10² g/cm³

= 22.67 g/cm³

So, the density of iridium metal is 22.67 g/cm³

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