In an electrically neutral atom, the number of
protons equals the number of neutrons.
protons equals the number of electrons.
neutrons equals the number of electrons.

A. Protons equals the number of neutrons
B. Protons equal the number of electrons
C. Neutrons equals the number of electrons

Answer: B

The international system of units is known as SI and is a metric system. Mostly used as a system of measurement. It is used in science, technology, and nearly in every part of the country. The system includes coherent units known as derived units.

Hence the option B is correct.

Learn more about the frequently used in chemical calculations.

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Answer:

8,3, 7,7

Explanation:

Answer:

1) The percentage of oxygen in dry air is _______

C. 21

2) The composition of the Earth’s earliest atmosphere was different to that of the present atmosphere. Which of these gases was present in large amounts in the Earth’s earliest atmosphere?

B. CARBON DIOXIDE

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have a nice day

Answer: The percentage of oxygen in dry air is .  21

Explanation:  Ammonia gases was present in large amounts  in the easth7s earliest atmosphere

Hope it will help you

Answer:

C

Explanation:

in the option C when we rearrange it then it will he C3H6O2

Answer:

yes its C

Explanation:

correct me if iam wrong

Answer:

Explanation:

Given : Density - 2.41 g/liter  

Temperature - 25° C  

Pressure : 770 mm Hg  

R = 0.0821 L atm mol-¹K-¹

Find : Molecular mass of gas

Solution : Ideal gas equation with respect to density will be : PM = dRT. In the formula, P is pressure, M is molecular mass, d is density, R is gas constant and T is temperature.

Keeping the values in equation-  

Pressure : 770 mm Hg = 1 atm  

Temperature : 273 + 25 = 298 K

M = dRT/P  

M = (2.41*0.0821*298)/1  

M = 58.96 gram/mol

Thus, the molecular mass of gas is 58.96 gram/mol.

Answer:

=0.15M

Explanation:

To get the moles of the unknown LiOH, calculate the number of moles of HCl in 12.3mL.

Using the stoichiometric coefficient, mole ratio 1:1.

This means that the number of moles is the same. This number of moles is contained in 18mL. Then Calculate the molarity (concentration) which is in 1000mL

See the explanation from the image I have shared with you for calculations.

Answer:

I think option two (2) is the correct answer

Answer:

C thermal

Explanation:

Answer:

937.5g

Explanation:

No of moles = mass ÷ molar mass

According to this question, there are 15moles of the compound; AlCl

Molar mass of AlCl = 27 + 35.5

= 62.5g/mol

Using n = m/M.M

15 = m/62.5

m = 15 × 62.5

m = 937.5g

Answer:

(i) specific heat

(ii) latent heat of vaporization

(iii) latent heat of fusion

Explanation:

i. Q = mcΔT; identify c.

Here, Q is heat, m is the mass, c is the specific heat and ΔT is the change in temperature.

The amount of heat required to raise the temperature of substance of mass 1 kg by 1 degree C is known as the specific heat.  

ii. Q = mLvapor; identify Lvapor

Here, Q is the heat, m is the mass and L is the latent heat of vaporization.

The amount of heat required to convert the 1 kg liquid into 1 kg vapor at constant temperature.  

iii. Q = mLfusion; identify Lfusion

Here, Q is the heat, m is the mass and L is the latent heat of fusion.  

Here, Q is the heat, m is the mass and L is the latent heat of vaporization.

The amount of heat required to convert the 1 kg solid  into 1 kg liquid at constant temperature.  

(i) c is the molar heat capacity of the substance.

(ii) Lvapor is the latent heat of evaporation of the substance

(iii) Lfusion is the latent heat of fusion of the substance

All the 3 equations fall under Calorimetry.

In all the equation Q is the amount of heat required.

(i) First equation represents the amount of heat required to raise the temperature of a substance of mass m.

                          Q = mcΔT

       here c is the molar heat capacity of the substance and ΔT is the chnage in temperature.

(ii) Second equation represents the amount of heat required to convert a substance of mass m from liquid phase to vapour phase.

                          Q = mLvapor

        here Lvapor is the latent heat of evaporation of the substance

during evaporation no change in temperature occurs.      

(iii) Third equation represents the amount of heat required to convert a substance of mass m from solid phase to liquid phase.

                          Q = mLfusion

        here Lfusion is the latent heat of fusion or melting of the substance

during fusion no change in temperature occurs.    

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Answer:

The pyruvate dehydrogenase kinase enzyme activity would increase, resulting in an inhibition of pyruvate dehydrogenase activity. ... An in vitro study shows that isocitrate dehydrogenase is activated in the citrate cycle.

Explanation:

i know the answer is a theory

Answer:

Weight = mass × gravitational

Weight = 60 kg × 9.8 ms²

= 588 N

Explanation:

hope it helps

Weight of the boy = Mass of the boy × g

= 60 × 9.8

= 588kgm/s²

= 588N

Answer:

-Reversal of the resting potential due to influx of sodium ions

-Mechanism that restores the resting membrane voltage and intracellular ionic concentrations

-Period during which potassium ions are diffusing out of the neuron because of a change in membrane permeability

-A brief reversal of membrane potential that travels along the axon

Explanation:

An action potential is a situation where the membrane potential is briefly reversed from -70mV to +30 mV

There are three steps of the moving action potential, including;

1) The depolarization step, where the membrane resting potential is reversed by the rush of sodium ions into a neuron

2) The repolarization, due to the closing of the voltage-gated sodium channels and the opening of the potassium channels, which is a mechanism that restores the membrane's resting voltage and the ionic concentration in the cell

3) Hyperpolarization, where due to some open potassium channels, there is an increased potassium permeability, and excessive efflux of potassium ions take place, which results in a dip in the membrane potential

4) The above three phases describe the phase of the action potential which is the brief reversal of membrane potential that travels along the axon

Explanation:

this is the reason why aluminium's boiling point is higher than that of sodium. sodium forms Na+ ions, therefore 1 electron is lost from each sodium atom, whereas aluminium forms Al3+ ions, so 3 electrons are lost for each Aluminum atom. The number of delocalised electrons therefore increases from sodium to aluminium, and charge density of the ions increases as the ionic charge increases and size decreases.

Answer:

[tex]\huge\color{cyan}{\colorbox{magenta}{Answer}}[/tex]

thank you

Answer:

0, +2

Explanation:

As a pure element, any element or simple compound has an oxidation number of 0. This makes it a lot easier, and can be applied for almost any element or compound that uses one atom, like F2, O3, Zn, Fe, etc. However, in compounds, Zinc's oxidation number tends to be +2, and this is just a rule that I memorized when I learned this topic. Please let me know if you still need help and I hope you understood!

As a pure element, the oxidation number of zinc is zero, but in compounds such as  [tex]ZnCO_3\\[/tex] its oxidation number is +2.

Oxidation number also called oxidation state, is the total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom.

As a pure element, any element or simple compound has an oxidation number of 0. This makes it a lot easier and can be applied for almost any element or compound that uses one atom, like [tex]F_2[/tex], [tex]O_3[/tex], Zn, Fe, etc.

However, in compounds, Zinc's oxidation number tends to be +2.

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Answer:

B. O2 is reduced when it accepts electrons and forms water.

Explanation:

During cellular respiration water is formed when oxygen receives electrons and picks up protons at the conclusion of the electron transport chain. The electron transport chain will stop functioning if there isn't enough oxygen to receive electrons (for example, because a person isn't breathing in enough oxygen), and ATP will no longer be created by chemiosmosis. Cells can't carry out the reactions they need to function if they don't even have enough ATP, and they may perish after a long period of time.

Answer:

Coriolis Effect

Explanation:

The Coriolis Effect is caused by Earths rotation. We can not only see this affecting how winds move, but also where storms form and the movement of  oceans currents.

Answer:

+3·F

Explanation:

The number of objects in the given system = 2 objects

The charge on each object are; q₁ = -Q, q₂ = -Q

The force acting between the objects = +F

The distance between the objects = 2·d

The formula for the force acting between two charged particles is given as follows;

[tex]F=K \times \dfrac{q_{1} \times q_{2}}{r^{2}}[/tex]

Therefore, we get;

[tex]F=K \times \dfrac{-Q \times -Q}{(2\cdot d)^{2}} = K \times \dfrac{Q^2}{4 \cdot d^2}[/tex]

By tripling the charge, q₁, on the first object, we get;

q₂ = 3 × (-Q)

[tex]F_2=K \times \dfrac{-3 \cdot Q \times -Q}{(2\cdot d)^{2}} = K \times \dfrac{3 \cdot Q^2}{4 \cdot d^2} = 3 \times +F = +3\cdot F[/tex]

Therefore, the new force between them, F₂ = +3·F

19. place moth balls in the closet and observe after several days.

20. whenever wax or a candle burns it turns from solid to liquid but again at room temperature it turns to solid

21. evaporation, condensation, precipitation

22. it produces new substances

23. vinegar Bubbles when baking soda is added

24. steam

Answer:

12 mL

Explanation:

Según la pregunta;

V / V% concentración del fármaco = 12%

volumen de la solución = 100 ml

De;

V / V% = volumen de fármaco / volumen de solución

volumen de fármaco = V / V% × volumen de solución

volumen de fármaco = 12/100 × 100

= 12 mL

Complete question is;

Glycerin, C3H8O3, is a nonvolatile liquid. What is the vapor pressure of a solution made by adding 164 g glycerin to 338 mL H2O ​at 39.8°C?

The vapor pressure of pure water at 39.8°C is 54.74 torr and its density is 0.0992 g/cm³

Answer:

28 torr

Explanation:

Let's first find the number of moles of water in 338 mL.

Molar mass of water = 18 g/mole

Formula for number of moles = mass/molar mass.

Mass = density × volume = 0.0992 × 338 = 33.5296 g

Thus;

Number of moles = 33.5296/18 = 1.863 moles.

Let's use the same procedure to find the Number of moles of glycerine.

Molar mass of glycerine from online values = 92.1 g/mol

Thus;

n_glycerine = (mass)/92.1

We have mass and density as 164 g and 0.0992 g/cm³ respectively.

n_glycerine = 164/92.1

n_glycerine = 1.78

Total moles of solution = 1.863 + 1.78 = 3.643 moles

We are told that The vapor pressure of pure water at 39.8°C is 54.74 torr

Thus, since water dominates, then vapour pressure of solution = (1.863/3.643) × 54.74 ≈ 28 torr

Answer:

8.87 × 10³ moles.

Explanation:

To convert number of molecules of sulfur hexafluoride (SF6) to moles (n), we divide by Avogadro's number (6.02 × 10²³)

That is; n = N ÷ nA

According to the question, 5.34 x 10^27 molecules of SF6 was given in this question. Hence, the number of moles it contains is given as:

n = 5.34 x 10^27 ÷ 6.02 × 10²³

n = 5.34/6.02 × 10^ (27-23)

n = 0.887 × 10⁴

n = 8.87 × 10³ moles.

Answer: The percentage by volume of alcohol will be 21%.

Explanation:

Given: Volume of solute = 14.7 [tex]cm^{3}[/tex]

Volume of solvent = 70 [tex]cm^{3}[/tex]

Formula used to calculate percentage by volume is as follows.

[tex]Percentage volume = \frac{volume of solute}{volume of solvent} \times 100[/tex]

Substitute the values into above formula as follows.

[tex]Percentage volume = \frac{volume of solute}{volume of solvent} \times 100\\= \frac{14.7 cm^{3}}{70 cm^{3}} \times 100\\= 21 percent[/tex]

Thus, we can conclude that the percentage by volume of alcohol will be 21%.

When the hematite particles rearrange to form a new substance", this statement describes chemical change.

A chemical change is a change of materials into another, new materials with different properties and one or more than one new substances are formed.

As a chemical changes is usually a change where a substance undergoes a chemical change and forms a new substance; which cannot be easily reversed into reactants by any simple physical methods.

In this example the hematite ore forms a new substance by an irreversible chemical change.

Hence, "The hematite particles rearrange to form a new substance", this statement describes chemical change.

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