2. As NH4OH is added to an HCl solution, the pH of the solution
A) increases as the OH- concentration decreases
B ) increases as the OH- concentration increases
C ) decreases as the OH- concentration decreases
D ) decreases as the OH- ion concentration increases

Answer:

20

Explanation:

Hi there!

We need to find the atomic number of an atom that has 20 protons and 20 neutrons

the atomic number of an atom is equivalent to the amount of protons an atom has, as the number of protons determines what element an atom is.

Since the atom has 20 protons, the atomic number of the said atom is 20

Hope this helps!  

Answer:

I hope that's what u were lookong for :))

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

Hope it helps

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:

1. Na2CO3 + 2HCl --> 2NaCl + CO2 + H2O

2. 2NaOH + H2SO4 --> Na2SO4 + H2O

3. CaCO3 + 2HCl --> CaCl2 + CO2 + H2O

4. 4Na + O2 --> 2Na2O

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

Answer:

the number of electrons in the cell

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.

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:

False

Explanation:

No, the mass of an electron is not equal to the mass of a neutron. Mass of neutron is greater than the mass of an electron.

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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Answer: 1.224 moles of [tex]Na_3N[/tex] were used.

Explanation:

We are given:

Volume of nitrogen gas produced = 13.7 L

At STP conditions:

22.4 L of volume is occupied by 1 mole of a gas

Applying unitary method:

13.7 L of nitrogen gas will be occupied by = [tex]\frac{1mol}{22.4L}\times 13.7L=0.612mol[/tex]

For the given chemical reaction:

[tex]2Na_3N\rightarrow 6Na+N_2[/tex]

By Stoichiometry of the reaction:

1 mole of nitrogen gas is produced by 2 mole of [tex]Na_3N[/tex]

So, 0.612 moles of nitrogen gas will be produced from = [tex]\frac{2}{1}\times 0.612=1.224mol[/tex] of [tex]Na_3N[/tex]

Hence, 1.224 moles of [tex]Na_3N[/tex] were used.

Answer:

Calculate the volume (in L) occupied by 3.40 g of NH3 at STP. (STP: 0 degree Celsius and 1 atmosphere of pressure).

Explanation:

To get the volume of ammonia gas at STP, calculate the number of moles of [tex]NH_3[/tex] in the given amount.

Number of moles of [tex]NH_3[/tex] gas is:

[tex]number of moles of NH_3 gas&=\frac{given mass of the gas}{its molecular mass} \\ &=\frac{3.40g}{17.0g/mol} \\&=0.2 mol.[/tex]

Since,

1 mol of any gas at STP occupies ------- 22.4 L of volume.

then,

0.2 mol of [tex]NH_3[/tex] occupies how much volume?

[tex]=>0.2 mol x \frac{22.4 L}{ 1.0 mol} \\=4.48 L[/tex]

Hence, the volume occupied by 3.40 g of ammonia at STP is --- 4.48 L.

Answer:

a

Explanation:

I'm not completely sure tho veary sorry if it's wrong

Answer:

the answer is C

Explanation:

as the yeast feeds on sugar and yields the ATP per glucose molecule and Carbon dioxide

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:

In the esterification reaction, an OH from the molecule acid and H from the alcohol form a molecule of water.

Ethanol and butanoic acid forms ethyl butanoate

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

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

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:

according to me its c part which is correct

Answer:

To determine the number of atoms of Boron that are present within 3.61 grams of Boron Trifluoride, it would be best to convert the grams to moles of the compound and then after that use the Avogadro's number to determine the number of molecules and then use the 1 to 3 ratio to determine the total number of Boron atoms.

Answer:

C thermal

Explanation:

Answer: they are held together by hydrogen bonds I believe

Explanation:

The strong bonds exist between water molecules.Because they are held together by hydrogen bonds. Option B is correct.

Hydrogen bonding is a bond between hydrogen atom, but rather a sort of dipole-dipole attraction between molecules.

The attractive force between a hydrogen atom covalently bound to a very electronegative atom such as an N, O, or F atom and another extremely electronegative atom causes it.

The strong bonds exist between water molecules.Because they are held together by hydrogen bonds. Hence,option B is correct.

Hence,option B is correct.

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i know the answer is a theory

Answer:

[tex]\boxed {\boxed {\sf SO_3}}[/tex]

Explanation:

An empirical formula shows the smallest whole-number ratio of the atoms in a compound.

So, we must calculate this ratio. Since we are given the amounts of the elements in moles, we can do this in just 2 steps.

The first step is division. We divide the amount of moles for both elements by the smallest amount of moles.

There are 0.300 moles of sulfur and 0.900 moles of oxygen. 0.300 is smaller, so we divide both amounts by 0.300

The next step is writing the formula. We use the numbers we just found as the subscripts. These numbers go after the element's symbol in the formula. Remember sulfur is S and there is 1 mole and oxygen is O and there are 3 moles.

This formula is technically correct, but we typically remove subscripts of 1 because no subscript implies 1 representative unit.

[tex]\bold {The \ empirical \ formula \ for \ the \ compound \ is \ SO_3}}[/tex]