chemistry question please help

Answer:

B. The VSEPR theory

Explanation:

The valence shell electron pair repulsion theory describes the way in which atoms are arranged within a molecule.

Answer:

B

Explanation:

The VSEPR theory

Answer:

5.720 m

Explanation:

Step 1: Given data

Step 2: Calculate the moles of solute

The molar mass of ammonium chloride is 53.49 g/mol.

153.0 g × (1 mol/53.49 g) = 2.860 mol

Step 3: Calculate the kilograms of solvent

We will use the relationship 1 kg = 1000 g.

500.0 g × (1 kg/1000 g) = 0.5000 kg

Step 4: Calculate the molality of the solution

m = 2.860 mol / 0.5000 kg = 5.720 m

Answer:

sulfur dioxide

Explanation:

Answer:

A: 15 protons, 16 neutrons, and 15 electrons

Explanation: An isotope of an element is when neutrons are taken away from the nucleus, or added to the nucleus.  

If you change the amount of protons in the nucleus, not only will the charge become positive due to their being one more proton than an electron, but the atom will change to a new element, Sulfur. If you change the electron count, that will just affect how prominent the negative charge is on the atom, whether it be more negative by adding an electron, or more postitive by removing an electron. Therefore, the amount of neutrons that you add to the nucleus of an atom, will change the isotope of the atom, and that's why the answer is A because every other answer changes the neutron count other than A.  

Answer:

[tex]pH=3.44[/tex]

Explanation:

Hello.

In this case, since the formic acid (HCHO2) is a weak acid and it is mixed with its conjugate base (CHO2⁻) in the form of NaCHO2, we can compute the pH via the Henderson-Hasselbach equation:

[tex]pH=pKa+log(\frac{[Base]}{[Acid]} )[/tex]

Whereas the concentration of both acid and base are computed considering final total volume of 75.0 mL after adding the volume of each solution as shown below:

[tex]n_{base}=0.500mol/L*0.0150L=7.50x10^{-3}mol\\\\n_{acid}=0.25mol/L*0.0600L=1.5x10^{-2}mol[/tex]

And the resulting concentrations upon the final volume:

[tex][Base]=\frac{7.50x10^{-3}mol}{0.0750L}=0.1M[/tex]

[tex][Acid]=\frac{1.5x10^{-2}mol}{0.0750L}=0.20M[/tex]

Thus, the pH is:

[tex]pH=3.74+log(\frac{0.10M}{0.20M} )\\\\pH=3.44[/tex]

Best regards.

Answer:

Natural catastrophes, such as hurricanes, floods, fires or earthquakes, among others, are events generated by nature itself that negatively impact the ecosystem, causing damage to the environment and the species that inhabit it, including the humans. Thus, for example, fires seriously affect the ecosystems on which they develop, destroying the biodiversity of vegetation and fauna that inhabit there, which threatens large numbers of species and puts a limit on their development and reproduction.

Answer:

Explanation:

The momentum of an object can be found by using the formula

momentum = mass × velocity

From the question the momentum of the runner will be 0 kgm/s since the runner's velocity is 0

Hope this helps you

Answer:

The correct answer is - sp hybridization.

Explanation:

The molecular structure line with a carbon bound to the hydrogen with the single sigma bond and with 2 pi bond and one single sigma bond with carbon Nitrogen triple covalent bond.

To calculate the hybridization of an element like carbon by adding the sigma bond and the lone pair of that atom as here in  HCN molecule, zero lone electrons and two sigmas bond the C atom includes sp-hybridized orbital.

The hybridization for the carbon (C) atom in HCN (hydrogen cyanide) is sp. Therefore, option D is correct.

The electron configuration of carbon is 1s² 2s² 2p², with four valence electrons. In HCN, carbon forms three sigma bonds: one with hydrogen (H) and two with nitrogen (N). The sigma bonds are formed by overlapping atomic orbitals.

In the process of hybridization, the carbon atom promotes one of its 2s electrons to a 2p orbital to create a set of four hybrid orbitals. In HCN, only three hybrid orbitals are involved in bonding. One sp hybrid orbital of carbon overlaps with the 1s orbital of hydrogen to form the C-H sigma bond. The other two sp hybrid orbitals of carbon overlap with two nitrogen atoms, forming the C-N sigma bonds.

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Answer:

oxygen

Explanation:

I dont know if you still need it but here it is

Answer:

1.2x1023 molecules

hope this helped!

Explanation:

1227.6

Answer:

I think it’s D.

Explanation:

Answer:

G. KBr

F. MgS

MgS is the insoluble product.

Explanation:

When 2 salts as potasium sulfide, K₂S and magnesium bromide, MgBr₂ react, a double replacement reaction occurs where cations (K⁺ and Mg²⁺) exchange places, as follows:

K₂S + MgBr₂ → 2 KBr + MgS

Thus, the two possible products are:

G. KBr

F. MgS

Now, based on solubility rules:

All compounds containing alkali metal ions (As K⁺) are solubles in water. KBr is soluble

And all sulfides except calcium, strontium and barium sulfide are insoluble.

Thus, the insoluble product is:

MgS

Answer:

Al = Reduced (Oxidizing agent)

Fe = Oxidized (Reducing agent)

Explanation:

Al became less positive meaning that it gained an electron and Fe became more positive meaning that it lost elections. remember OIL RIG. Oxidation in loss of electrons and Reduction involves gain of electrons

Answer: The answer would be Fe.

Explanation: As "Fe" loses electrons, it becomes the reducing agent.

Answer:

true

Explanation:

the way the place grew back to life my g

Answer:

True

Explanation:

Secondary succession is when a terrain grows again after it's been destroyed.

Answer:

Explanation:

SnF₂ + 2HF = H₂Sn + 4F

mol weight of SnF₂ = 156.7

mol weight of HF = 20

156.7 gram of SnF₂ reacts with 40 grams of HF

4.44 gram of SnF₂ reacts with 40 x 4.44 / 156.7 grams of HF

= 1.13 grams of HF .

Answer:

Exothermic Reaction

Explanation:

The increase in temperature is as a result of the release of energy due to the dissolving of the NaOH pellets in water. This is an example of exothermic reactions.

They are easy to identify as the surroundings of the system becomes hot due to the release of the energy.

Answer:

According to my research there are 2 answers present.

Explanation:

Bromine as well as mercury is a nonmetallic liquid at room temperature

Answer:

product

Explanation:

Chemical reactions are said to be the formation of the products from the reactants. "In a chemical reaction, two reactants mix. The resulting substance is called a product." Thus, option C is correct.

A chemical reaction has been defined as the rearrangement of the atoms of the reactant molecules to result in new substances that differ in chemical properties and compositions. This results in the chemical transformation that results in product formation.

The products produced are new substances that are formed by the breaking or the combination of two or more reactants. The molecules of the reactant undergo collision that forms or breaks the bonds of the reactants.

The products produced are different in chemical properties and composition from the reactants it undergoes chemical changes. An example is iron rust, here iron undergoes oxidation to produce rust that is irreversible changes.

Therefore, option C. product is formed by mixing two or more reactants in a chemical reaction.

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Answer:

The major advantage of using ground glassware in the organic chemistry laboratory is that the joints can quickly and easily fit to other apparatus so that various reactions can be conducted from these various assembling of apparatuses.

Explanation:

Ground glass is glass whose polished surface has been ground to produce a rough finish.

Most organic chemistry laboratory glasswares are designed with ground glass joints. The joints are leak-tight and have outer (female) and inner (male) joints that can be tightly connected together.

These glassware are very important in the organic chemistry laboratory because they can be assembled and disassembled for various reactions conducted in the laboratory without having to have a specific custom-made glassware for each reaction or synthesis process performed in the laboratory. For example, a Liebig condenser can be used for various distillation reactions in the laboratory due to its joint that can be fitted to other apparatus in these reactions.

Also, ground glassware joints are chemical resistant and heat resistant unlike corks or rubber bungs and glass tubes.

Answer:

To prevent the spread of germs.

Explanation:

Answer:

B. freezing

Explanation:

During freezing, atoms lose energy. In this process, the molecules lose heat energy and they cool down. This reduces randomness of the matter.

Answer:

B)Freezing

Explanation:

just took the test edge 2021

Answer:

Ca + S -----> CaS

Explanation:

Since it is balanced you don't need to multiply it any more.

Solid calcium reacts with solid sulfur to produce solid calcium sulfide. The balanced equation for this reaction can be given as Ca + S → CaS.

An equation for just a chemical reaction is said to be balanced if both the reactants as well as the products have the same number of atoms and total charge for each component of the reaction. In other words, both sides of a reaction have an equal balance of mass and charge.

The ingredients and outcomes of a chemical reaction are listed in an imbalanced chemical equation, but the amounts necessary to meet the conservation of mass are not specified. Solid calcium reacts with solid sulfur to produce solid calcium sulfide. The balanced equation for this reaction can be given as Ca + S → CaS.

Therefore, the balanced equation for this reaction can be given as Ca + S → CaS.

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The empirical formula of the compound obtained when 2.97 g of iron combined with oxygen to produce 4.25 g of iron oxide is Fe₂O₃

Mass of Fe = 2.97 g

Mass of compound = 4.25 g

Mass of O = (Mass of compound) – (Mass of Fe)

Mass of O = 4.25 – 2.97

Fe = 2.97 g

O = 1.28

Divide by their molar mass

Fe = 2.97 / 56 = 0.053

O = 1.28 / 16 = 0.08

Divide by the smallest

Fe = 0.053 / 0.053 = 1

O = 0.08 / 0.053 = 1.5

Multiply by 2 to express in whole number

Fe = 1 × 2 = 2

O = 1.5 × 2 = 3

Therefore, the empirical formula of the compound is Fe₂O₃

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Considering the definition of empirical formula,  

The empirical formula is the simplest expression to represent a chemical compound, which indicates the elements that are present and the minimum proportion in whole numbers that exist between its atoms, that is, the subscripts of chemical formulas are reduced to the most integers. small as possible.

In this case, in first place you know:

Then, you need to express the mass into percentage as follow:

Assuming a 100 grams sample, the percentages match the grams in the sample. So you have 69.88 grams of iron and 30.12 grams of oxygen.

Then it is possible to calculate the number of moles of each atom in the molecule, taking into account the corresponding molar mass:

The empirical formula must be expressed using whole number relationships, for this the numbers of moles are divided by the smallest result of those obtained. In this case:

Finally all coefficients are multiplied by a whole number to ensure that the smallest proportion of whole number subscripts is obtained. In this case, it is multiplied by 2:

Therefore the Fe : O mole ratio is 2:3

Finally, the empirical formula is Fe₂O₃.

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Answer:

It will take 19.9 hours to fill the cubic.

Explanation:

First, we can find the volume of the cubic.

[tex]V_{c}=18.7^{3}ft^{3}=6539.2 ft^{3}=1.85*10^{8} ml[/tex]

Let's multiple this volume times the density

[tex]V_{c}*\rho=1.85*10^{8} ml * 1.49 g/ml = 2.76*10^{8} g[/tex]

If we divide the spilling rate by V times density we will have:

[tex]t=\frac{V_{c}}{\rho R}=2.76*10^{5} kg/3.85kg/s=71688.3 s = 19.9 h[/tex]

Therefore, it will take 19.9 hours to fill the cubic.

I hope it helps you!            

The study of chemicals and bonds is called chemistry. when the amount reactant and the product is equal is said to be equilibrium.

The correct answer is 19.9h.

The formula used to solve the question is as follows:-

[tex]D= \frac{M}{V}[/tex]

The data is given as follows:-

The density of the is as follows:-

[tex]V*D =1.85*10^8 *1.49 =2.76*10^8[/tex]

Hence, the time will be as follows:-

[tex]t=\frac{V_c}{Dr}\\ \\=\frac{2.76*10^5}{3.85} \\ = 71688.3s\\=19.9h[/tex]

Hence, the correct time is 19.9h.

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Answer:

2.31 g

Explanation:

Step 1: Given data

Step 2: Calculate the mass of water that can be vaporized with 1250 calories of energy

We will use the following expression.

Q = ΔH°vap × m

m = Q/ΔH°vap

m = 1250 cal/(540 cal/g)

m = 2.31 g

Answer:

Q1: 4

Q2: 2

Q3: 2

Explanation: