Which of these is correct please help

Answer:

15g

Explanation:

First, you need to correct the answer to the previous question. The percentage by mass of Mg in MgO =

Mg = 24.3 amu

O = 16.0 amu

The total mass of MgO = 40.3 amu

To calculate the percent composition of Mg:

% = 24.3/40.3 x 100

% = 60

To calculate the mass of Mg needed to make 25g of MgO:

x/25g = 60%/100%

100x = (25)(60)

100x = 1500

x = 15g

Answer:

could occur at any temperature.

Explanation:

The spontaneity of a reaction is what determines whether the reaction will occur or not. A spontaneous reaction occurs easily.

The spontaneity of a reaction is predicted by the sign of ∆G.

When ∆G is positive, the reaction is not spontaneous. When ∆G is negative, the reaction is spontaneous.

Note that;

∆G= ∆H - T∆S

Where;

∆H = Change in enthalpy

∆S = Change in entropy

T= temperature

If ∆H is unfavourable and ∆S is favourable, the reaction can proceed at all temperatures because ∆G will always be negative.

It should be noted that a process that is unfavorable as regards to enthalpy, but favorable with respect to entropy could occur at any temperature.

Enthalpy(∆H) serves as amount of internal energy that a compound has, entropy( ∆S)  on the other hand serves as intrinsic disorder within the system.

However, spontaneity of a reaction determines likely hood of occurrence of a reaction, when the process is spontaneous, it makes the reaction to occurs easily.

We can conclude that whenever enthalpy is unfavourable and entropy of a system is favourable, then the spontaneity will be negative and the reaction will occur at any temperature.

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Answer:

If you're indoors, stay inside. If you're outside, stay outside. If you're indoors, stand against a wall near the center of the building, stand in a doorway, or crawl under heavy furniture (a desk or table). Stay away from windows and outside doors.

Answer

Answer:

irregular galaxy

pls give brainliest :)

Answer:

irregular galaxy

it is undefined shape

Answer:

When an atom has an equal number of electrons and protons, it has an equal number of negative electric charges (the electrons) and positive electric charges (the protons). The total electric charge of the atom is therefore zero and the atom is said to be neutral.

I HOPE THIS HELPS !!!!!!!!!!!

Answer:

1.Physical change

2. Chemical change

3. Heat

4.photosynthesis

5. composition

Answer:

29.41% of Calcium and 47.04% of Oxygen

Explanation:

The percent composition of an atom in a molecule is defined as 100 times the ratio between the mass of the atom and the mass of the molecule.

The mass of the molecule of the problem (Ore) is 46.28g. That means the percent composition of Calcium is:

13.61g / 46.28g * 100 = 29.41% of Calcium

And percent composition of Oxygen is:

21.77g / 46.28g * 100 = 47.04% of Oxygen

Answer:

0.68

Explanation:

This is because the formula for finding density is mass/volume. Therefore the equation becomes 5.6/8.2 giving you 0.68

Answer:

Divide the mass of the solute by the total volume of the solution. Write out the equation C = m/V, where m is the mass of the solute and V is the total volume of the solution. Plug in the values you found for the mass and volume, and divide them to find the concentration of your solution.

Answer:

The law of reciprocal proportions states that if two elements react individually with a given weight of a third element, the ratio of the masses with which they combine with the third element are either the same or a simple multiple of the ratio of the masses with which they combine with each other

The compounds formed includes;

1) Nitric oxide, NO

Nitrogen = 46.66% × 30.01 = 14

Oxygen = 53.34% × 30.01 = 16

2) Water, H₂O

Hydrogen = 11.21% × 18.01528 = 2

Oxygen = 88.79% × 18.01528 ≈ 16

3) Ammonia, NH₃

Hydrogen = 17.78% × 17.031 ≈ 3

Nitrogen = 82.22% × 17.031 ≈ 14

The ratio of nitrogen to oxygen in nitric oxide = 14:16 = 7:8

The ratio of nitrogen to hydrogen in ammonia = 14:3

The ratio in which hydrogen and oxygen combine with nitrogen = 3/16

The ratio of hydrogen and oxygen combine with each other in water = 2/16

Therefore, the ratio with which hydrogen and oxygen combine with nitrogen, is (2/3) times the ratio with which they combine with each other, which verifies the law of reciprocal proportions

Explanation:

Answer:

A

Explanation:

Hydrogen bonds are intermolecular forces of interaction that exist between molecules of a substance in which hydrogen is bonded to a highly electronegative atom. Hydrogen bonds are strong intermolecular forces and account for high melting and boiling points of small molecules such as water. They stem from dipole-dipole interaction between molecules of a substance.

Metallic bonds are bond forces which exist in a metal. Metal cations are held together by a sea of electrons via electrostatic interaction.

The ionic bond is formed by transfer of electrons from one atom to another leading to the formation of an ion pair held together by electrostatic attraction.

Metallic bonds and hydrogen bonds are much weaker than ionic bonds. Ionic compounds are known to have high melting and boiling points.

Explanation:

The given chemical equation is:

[tex]2A + 4B -> 2C + 2D[/tex]

The rate of the reaction is 0.0352 M/s.

During the course of the reaction, the rate of reactants decreases, and the rate of products increases.

The rate of disappearance of B is shown below:

[tex]rate=-\frac{1}{4} \frac{d[B]}{dt}[/tex]

So, rate of change of B is :

[tex]rate of change of B =- rate * 4\\=-0.0352 M/s * 4\\=-0.1408M/s\\\\=-0.141M/s[/tex]

Option C.

In the given reaction, rate of change of reactant B is equal to -0.141 M/s.

Rate of any chemical reaction defines the speed of the completion of that reaction.

In the question given reaction is:

2A + 4B ----> 2C + 2D

Rate of reaction = 0.0352 M/s.

Rate of the reaction with respect to the reactant B is written as:

Rate = [tex]${\rm{ - }}\frac{{\rm{1}}}{{\rm{4}}}\frac{{\left[ {{\rm{dB}}} \right]}}{{{\rm{dT}}}}$[/tex], where negative sign shows the disappearance of reactant B.

Rate of change of B i.e. [tex]$\frac{{{\rm{dB}}}}{{{\rm{dT}}}}$[/tex] =  4 × (-rate)

[tex]$\frac{{{\rm{dB}}}}{{{\rm{dT}}}}$[/tex] =  4 × (-0.0352) = -0.1408 = -0.141 M/s

Hence, -0.141 M/s is the rate of change of B.

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Answer:

0.017g/mol

Explanation:

according to the mole concept to calculate the number of moles of a substance you use the formula

number of moles= mass/molecular mass

=4.5g/254g/mole

=0.017moles

I hope this helps and sorry if it's wrong

Answer:

The Cavendish experiment, performed in 1797–1798 by English scientist Henry Cavendish, was the first experiment to measure the force of gravity between masses in the laboratory and the first to yield accurate values for the gravitational constant

Explanation:

I think that's correct

1. Cl2 + H2O → HOCl + HCl

2. Tooth decay starts when when the pH of the mouth is lower than 5.5. Tooth enamel is made up of calcium phosphate and it is one of the hardest substances of the body. But it is corroded when the pH is less than 5.5. The bacteria of our mouth produce acids by degradation of sugar and food particles remaining in our mouth after eating food.

3. Fluorine salts are added in toothpaste to protect our teeth from tooth decay. Fluorine salts are mildly basic, so they neutrelise the acid in our mouth that leads to tooth decay.

4. Tincture of iodine is iodine, pottasium iodide and sodium iodide dissolved in ethanol. Iodine acts in an antiseptic manner by destroying microbial proteins and DNA.

5. Tincture of iodine is clear and reddish brown liquid.

Answer:

A

Explanation:

The instrument in which the washer works as a valve is  A ; syringe

Each instrument listed have a washer and a valve, but of all the instruments listed above the instrument that its washer works also as a valve is the syringe.

A syringe is composed of a thin tube and a thinner hollow needle attached to the end of the thin tube. the needle is used and take in liquids and also expel liquids from the syringe ( i.e. washer and valve )

hence the instrument that its washer also functions as a valve is the syringe.

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Answer:

132.17amu

Explanation:

(14.01+1.01 multiplied by 4)=18.05×2=36.1

36.1+32.07= 68.17

16.00×4=64

68.17+64=132.17

Answer:

132.17 amu

Explanation:

just took the test. got 100

Answer:

Pottasium

Explanation:

because it is the nineteenth element

Answer:

The answer is B. Potassium.

Explanation: Potassium has 19 electrons that are organized like the image if you count the electrons on each obital. This answer is correct on edge 2020. Hope this helps!

Answer:

Answer: They are attracted to each other due to their electrostatic attraction. All that means is the hydrogen atom is positively charged, while the oxygen atom is negatively charged. ... The hydrogen of one water molecule will bond to the oxygen atom of another molecule.

Answer:

They are attracted to each other due to their electrostatic attraction. All that means is the hydrogen atom is positively charged, while the oxygen atom is negatively charged. ... The hydrogen of one water molecule will bond to the oxygen atom of another molecule.

Explanation:

Answer:

b is the answr

Explanation:

The correct answer is Option (B) Enrichment of Uranium-235 is done.

Hence Option (B) is correct because enrichment of uranium-235 is achieved by the process of conversion So , It does not facilitate containment

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#SPJ2

Answer:

∆H0 = -222kJ/mol

Explanation:

Using Hess's law, we can find the ΔH of a reaction from the sum of another related reactions as follows:

Using the reactions:

(1) C(s) + O2(g) → CO2(g) ∆H0= -394 KJ/mol

(2) CO(s) + 1/2 O2(g) → CO2(g) ∆H0= -283 KJ/mol

Twice (1):

2C(s) + 2O2(g) → 2CO2(g) ∆H0= 2*-394 KJ/mol = -788kJ/mol

The inverse reaction of (2):

-(2) CO2(g) → CO(g) + 1/2 O2(g) ∆H0= 283 KJ/mol

Twice this reaction:

2*-(2) 2CO2(g) → 2CO(s) + O2(g) ∆H0= 2*283 KJ/mol= 566kJ/mol

Now, the sum of 2*(1) - 2*(2) produce:

2C(s) + 2O2(g) + 2CO2(g)→ 2CO2(g) + 2CO(g) + O2(g) ∆H0= -788kJ/mol +  566kJ/mol

Subtracting the molecules that ar in both sides of the reaction:

2C(s) + O2(g) → 2CO(g) ∆H0 = -222kJ/mol

Answer:

its D

Explanation:

Took the test

The specie whose concentration is plotted is D. The rate of reaction is how quickly or slowly hat a reaction proceeds.

The term rate of reaction refers to how quickly or slowly hat a reaction proceeds. A reaction rate plot involves the concentration of the species plotted against time.

Now we can see from the plot that concentration is increasing with time. Since the concentration of products increases with time, then the specie whose concentration is plotted is D.

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Answer: The volume of 9.7 tons of given ethylene glycol is 0.0079 [tex]m^{3}[/tex].

Explanation:

Given: Density = 1.11 [tex]g/cm^{3}[/tex]

Mass = 9.7 tons

Convert tons into lb as follows.

[tex]1 ton = 2 \times 10^{3} lb\\9.7 ton = 9.7 ton \times 2 \times 10^{3} \frac{lb}{1 ton}\\= 19.4 \times 10^{3} lb[/tex]

Now, lb is converted into kg as follows.

[tex]1 kg = 2.2046 lb\\1 lb = 0.453592 kg\\19.4 \times 10^{3} lb = 19.4 \times 10^{3} lb \times 0.453592 \frac{kg}{1 lb}\\= 8.79 kg[/tex]

1 kg = 1000 g

So, 8.79 kg = 8790 g

Density is the mass of a substance divided by its volume. Hence, volume of ethylene glycol is calculated as follows.

[tex]Density = \frac{mass}{volume}\\1.11 g/cm^{3} = \frac{8790 g}{volume}\\volume = 7918.92 cm^{3} (1 cm^{3} = 10^{-6} m^{3})\\= 0.0079 m^{3}[/tex]

Thus, we can conclude that the volume of 9.7 tons of given ethylene glycol is 0.0079 [tex]m^{3}[/tex].

Answer:

What atoms are present in carbon tetrachloride?

There is 1 carbon, and 4 chlorine atoms (or chloride ions if you want to get technical). Tetra means 4 in Greek.

hope that helps❤

Answer:

there are no calcium atoms of n carbon tetrachloride

Answer:

The answer is "Auger".

Explanation:

The Auger effect is an effect size when the vacancy of even an atom throughout the inner shell was complemented by the release of even an electron from the same atom. Whenever a central electron is lost, a higher energy level electron can drop into the void and release energy, which can be the result.

Answer:

Triads were groups of 3 elements with similar chemical and physical properties. Beryllium, magnesium, and calcium are all earth alkalis found in the earth

Explanation:

While picking up a buret, an unknown solution left by a previous solution drips onto your hand - Gloves

While pulling an empty beaker off the shelf at the beginning of lab, it slips out of your hand onto the floor - Closed-toe shoes

While checking on a stirring solution, the solution splashes up towards your face - Goggles

While transferring a solution from a flask to a beaker, the solution accidentally spills down the front of the lab bench - Lab coat

Explanation:

So, according to the question. the matches will be:

While picking up a buret, an unknown solution left by a previous solution drips onto your hand - Gloves

While pulling an empty beaker off the shelf at the beginning of lab, it slips out of your hand onto the floor - Closed-toe shoes

While checking on a stirring solution, the solution splashes up towards your face - Goggles

While transferring a solution from a flask to a beaker, the solution accidentally spills down the front of the lab bench - Lab coat

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