7th grade science lol help​

Answer:

A mole ratio is ​the ratio between the amounts in moles of any two compounds involved in a chemical reaction.

Mole ratios are used as conversion factors between products and reactants in many chemistry problems.

Explanation:

Answer:

In summer, it typically rains less than 5 cm (<2 inches), while in winter it rains 25–44 cm (10–17 inches).

Explanation:

because tundra vegetation is mostly found in desert areas

Answer:

The Lewis structure for the sulfate ion consists of a central sulfur atom with four single bonds to oxygen atoms. This yields the expected total of 32 electrons. Since the sulfur atom started with six valence electrons, two of the S-O bonds are coordinate covalent.

Explanation:

Then that means it has both.

Answer:

alpha particle needs to be added to the equation.

Explanation:

Given;

atomic mass of Americium = 241

atomic mass of neptunium = 237

The difference in atomic mass of the radioactive elements given is calculated as;

241 - 237 = 4

The particle with atomic mass of 4 is alpha particle usually represented with helium atom.

Am²⁴¹ -----> He⁴ + Np²³⁷

Thus, alpha particle needs to be added to the equation.

Answer:

4/2 HE

Explanation:

a p e x!

Why recycling isn't working in the U.S.

Many recyclables become contaminated when items are placed in the wrong bin, or when a dirty food container gets into the recycling bin. Contamination can prevent large batches of material from being recycled. Other materials can't be processed in certain facilities.

Answer:

Attached picture.

Explanation:

(1) Ksp equals the product of [Co 2+][CO3 2-]. CoCO3 is excluded from the equilibrium expression because it is a pure solid. The mole ratio of Co 2+ and CO3 2- is 1:1 so their molar solubilities are the same.

(2) There is an initial concentration of 0.10 M Co 2+ so write that in the "I" row for Co 2+ on the ICE table. When you find the zeros of the quadratic when solving for "s", take the positive value rather than the negative value because concentration cannot be negative.

(3) Extra products will cause the equilibrium to consume products and form reactants. So the reverse reaction will occur faster than the forward reaction. More products mean an increased Q value compared to K, since the numerator of [tex]K = \frac{[products]}{[reactants]}[/tex] increases.

Answer:

Bubbling can indicate a chemical reaction

Explanation:

Chemical reaction takes place with the beginning of bubbles and foam when hydrogen peroxide is put onto an open wound. This compound does not only heal the wound but also damages the body as it also kills the nearby healthy cells.

Chemical reaction is a process which leads to chemical transformation of a chemical substance into another.

Hydrogen peroxide bubbles when it comes into contact with an enzyme called catalase. Most of the cells in the body contain catalase enzyme, so whenever the tissue is damaged, the enzyme catalase is released from the cell and it becomes available to react with the peroxide ion.

Hydrogen peroxide applied on a cut produces a white, fizzling foam which is actually a sign that the solution is killing the bacteria as well as the healthy cells around it.

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Answer:

The limiting reactant is: H₂O

265.3 g of K₂Sn(OH)₆ are formed in the reaction.

Explanation:

The reaction is:

Sn(s) + 2KOH (aq) + 4H₂O(l)  → K₂Sn(OH)₆ (s) + 2H₂ (g)

The first step to solve is to determine the moles of each reactant:

We controlled that reaction is ballanced.

122 g . 1mol / 118.71g = 1.03 moles of Sn

134g . 1mol /56.1g = 2.39 moles of KOH

63.9 g .1mol /18g = 3.55 mol of water

Stoichiometry is 1:2:4.

Sn is the lowest reactant and water, the highest, but I can see, that water is the limiting.

1 mol of Sn needs 4 moles of H₂O to react

Then, 1.03 moles of Sn may react to (1.03 . 4)/1 = 4.12 moles.

We only have 3.55 moles. It's ok.

2 moles of KOH need 4 moles of H₂O to react

Then, 2.39 moles of KOH may react to (2.39 . 4) /2 = 4.78 moles.

We only have 3.55, there's no enough water.

So 4 moles of water can produce 1 mol of potassium hydroxystannate

Then, 3.55 moles of H₂O may produce (3.55 . 1)/4 = 0.8875 moles.

We convert moles to mass: 0.08875 mol . 298.91g /1mol =265.3g

Answer:

Explanation:

It is 11

Answer: The mass of sodium acetate anhydrous required is 0.820 g

The mass of sodium acetate trihydrate required is 1.36 g

The mass of Iron (III) chloride required is 2.70 g

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.

[tex]Molarity=\frac{n\times 1000}{V_s}[/tex]

where,

n = moles of solute

= volume of solution in ml

1. moles of =

Now put all the given values in the formula of molarity, we get

[tex]0.100=\frac{x\times 1000}{82.03\times 100.0}[/tex]

[tex]x=0.820g[/tex]

Therefore, the mass of sodium acetate anhydrous required is 0.820 g

2.   moles of [tex]CH_3COONa.3H_2O[/tex] = [tex]\frac{\text {given mass}}{\text {Molar mass}}=\frac{xg}{136.08g/mol}[/tex]

Now put all the given values in the formula of molarity, we get

[tex]0.100=\frac{x\times 1000}{136.08\times 100.0}[/tex]

[tex]x=1.36[/tex]

Therefore, the mass of sodium acetate trihydrate required is 1.36 g

3. moles of [tex]FeCl_3.6H_2O[/tex] = [tex]\frac{\text {given mass}}{\text {Molar mass}}=\frac{xg}{g/mol}[/tex]

Now put all the given values in the formula of molarity, we get

[tex]0.100=\frac{x\times 1000}{270.33\times 100.0}[/tex]

[tex]x=2.70g[/tex]

Therefore, the mass of Iron (III) chloride required is 2.70 g

Answer:

THE ANSWER IS 1.167L

Explanation:

Answer:

C.

Explanation:

Answer:

HCO₂

Explanation:

From the information given:

The mass of the elements are:

Carbon C = 26.7 g;     Hydrogen H = 2.24 g     Oxygen O = 71.1 g

To determine the empirical formula;

First thing is to find the numbers of moles of each atom.

For Carbon:

[tex]=26.7 \ g\times \dfrac{1 \ mol }{12.01 \ g} \\ \\ =2.22 \ mol \ of \ Carbon[/tex]

For Hydrogen:

[tex]=2.24 \ g\times \dfrac{1 \ mol }{1.008 \ g} \\ \\ =2.22 \ mol \ of \ Hydrogen[/tex]

For Oxygen:

[tex]=71.1 \ g\times \dfrac{1 \ mol }{1.008 \ g} \\ \\ =4.44 \ mol \ of \ oxygen[/tex]

Now; we use the smallest no of moles to divide the respective moles from above.

For carbon:

[tex]\dfrac{2.22 \ mol \ of \ carbon}{2.22} =1 \ mol \ of \ carbon[/tex]

For Hydrogen:

[tex]\dfrac{2.22 \ mol \ of \ carbon}{2.22} =1 \ mol \ of \ hydrogen[/tex]

For Oxygen:

[tex]\dfrac{4.44 \ mol \ of \ Oxygen}{2.22} =2 \ mol \ of \ oxygen[/tex]

Thus, the empirical formula is HCO₂

Answer:

14

Explanation:

Step 1: Calculate the moles corresponding to 25 g of Ba(OH)₂

The molar mass of Ba(OH)₂ is 171.34 g/mol.

25 g × 1 mol/171.34 g = 0.15 mol

Step 2: Calculate the molar concentration of Ba(OH)₂

Molarity is equal to the moles of solute divided by the liters of solution.

[Ba(OH)₂] = 0.15 mol/0.250 L = 0.60 M

Step 3: Calculate the molar concentration of OH⁻

Ba(OH)₂ is a strong base according to the following equation.

Ba(OH)₂ ⇒ Ba²⁺ + 2 OH⁻

The molar ratio of Ba(OH)₂ to OH⁻ is 1:2. The molar concentration of OH⁻ is 2/1 × 0.60 M = 1.2 M.

Step 4: Calculate the concentration of H⁺

We will use the ionic product of water expression.

Kw = 1.0 × 10⁻¹⁴ = [H⁺] × [OH⁻]

[H⁺] = 1.0 × 10⁻¹⁴/[OH⁻] = 1.0 × 10⁻¹⁴/1.2 = 8.3 × 10⁻¹⁵ M

Step 5: Calculate the pH of the solution

We will use the definition of pH.

pH = -log [H⁺] = -log 8.3 × 10⁻¹⁵ = 14

Answer:

C). Electronegativity.

Explanation:

'Electronegativity' is described as the tendency or a measure of the ability of an atom or molecule to attract electrons that leads to the formation of chemical bonds. It is denoted by 'χ', a Greek letter. The elements like Fluorine having a very high rate of electronegativity, its atom would attract the electrons more strongly while the elements with lesser electronegativity like Cesium would possess a lesser tendency to attract electrons towards it in order to form a bond. Thus, option C is the correct answer.

Answer:

894 deg K

Explanation:

The computation is shown below:

Given that

V1 denotes the initial volume of gas = 2.00 L  

T1 denotes the initial temperature of gas = 25 + 273 = 298 K  

V2 denotes the final volume of gas  = 6.00 L  

T2 = ?

Based on the above information

Here we assume that the pressure is remain constant,

So,  

V1 ÷ T1 = V2 ÷ T2  

T2 = T1 × V2 ÷ V1

= (298)(6) ÷ (2)

= 894 deg K

Answer:

4.5M

Explanation:

The solution was diluted from 2.0L to 3.0L, the dilution factor was:

3.0L / 2.0L = 1.5.

That means the solution was diluted 1.5 times.

As the final molarity of the diluted solution is 3.0M, the initial molarity of the solution was:

3.0M * 1.5 =

The correct answer is solution B!

Answer:

The number of protons in one atom of an element determines the atom's identity, and the number of electrons determines its electrical charge. The atomic number tells you the number of protons in one atom of an element. It also tells you the number of electrons in a neutral atom of that element.

Explanation:

[tex]V = \text{133 mL}[/tex]

[tex]\rho = \text{0.789 g/mL}[/tex]

[tex]m[/tex]

[tex]\rho = \frac{m}{V}[/tex]

[tex]m = \rho V[/tex]

[tex]m = (\text{0.789 g/mL})(\text{133 mL})[/tex]

[tex]\boxed{m = \text{105 g}}[/tex]

Ethanol is a common laboratory solvent and has a density of 0.789 g/mL.  105g is the mass, in grams, of 133 mL of ethanol.

In physics, mass is a quantitative measurement of inertia, a basic characteristic of all matter. It essentially refers to a body of matter's resistance to changing its speed or location in response to the force that is applied. The change caused by a force applied is smaller the more mass a body has.

The kilogram, which would be specified as equivalent to 6.62× 10³⁴ joule second in terms of Planck's constant, is the unit of mass inside the International Units System (SI).

density = mass / volume

mass =density× volume

         = 0.78× 1.33

         =105g

Therefore, 105g is the mass.

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Answer:

Water acts as a base in the presence of a strong acid

Explanation:

Water,being an amphoteric compound, can act both as an acid and as a base.

In the presence of an acid , water acts as a base but in the presence of a base, water acts as an acid.

Answer:

Convergent Plate Boundaries

Explanation:

I hope this helps :)

Answer:

[tex]\boxed {\boxed {\sf \frac {1}{3} \ mol \ Al_2O_3 \approx 0.34 \ mol \ Al_2O_3}}[/tex]

Explanation:

We will use stoichiometry to solve this problem. The reaction given has a formula of

[tex]4Al+3O_2 \rightarrow 2Al_2O_3[/tex]

The coefficients tell us the number of moles necessary for the reaction.

The reaction requires 3 moles of oxygen to produce 2 moles of aluminum oxide. We can make a ratio.

[tex]\frac {3 \ mol \ O_2}{ 2\ mol \ Al_2O_3}}[/tex]

Since we are doing the reaction with 0.5 moles of oxygen, we multiply the ratio by that number.

[tex]0.5 \ mol \ O_2 *\frac {3 \ mol \ O_2}{ 2 \ mol \ Al_2O_3}}[/tex]

Flip the ratio so the moles of oxygen cancel each other out.

[tex]0.5 \ mol \ O_2 *\frac {2 \ mol \ Al_2O_3}{ 3 \ mol \ O_2}}[/tex]

[tex]0.5 *\frac {2 \ mol \ Al_2O_3}{ 3 }[/tex]

[tex]\frac {1 \ mol \ Al_2O_3}{ 3 }[/tex]

[tex]\frac {1}{3} \ mol \ Al_2O_3 = 0.33333 \ mol \ Al_2O_3 \approx 0.34 \ mol \ Al_2O_3[/tex]

0.5 moles of oxygen produces 1/3 or approximately 0.34 moles of aluminum oxide.

Answer:

Calcium flouride?

Explanation:

Quite self explanatory

Answer:

a)567mg

b)0.567 grams

Explanation:

There are 7 days in a week, so we multiply the number of weeks by the number of daily dosage.

81mg*7=567mg

1 gram is 1000 mg

we divide 567 by 1000 to get the value in grams

Answer:

0 587 mL

Explanation:

First we convert 180 grams of HCl into moles, using its molar mass:

Now we can use the number of moles and the given concentration to calculate the required volume, applying the definition of molarity:

Finally we convert liters into milliliters:

The closest answer is option C, 587 mL.

The volume needed to make an 8.40 M solution of HCl is 0.587 ml.

The correct option is C.

HCl is a strong acid. It is present in our stomach to help in digesting food.

Step1: covert 180 grams into moles

Molar mass of HCl is 36.46 g

[tex]\dfrac{180 g}{36.46 g/mol } = 4.94\; mol\; HCl[/tex]

Step2: calculate the molarity

[tex]\rm Molality = \dfrac{mol}{L}\\\\\rm L = \dfrac{4.94 mol }{8.40 M} = 0.588 L\\[/tex]

Covert the liters into ml

[tex]\dfrac{0.588 L}{1000} = 588 mL[/tex]

Thus, the volume of the solution is 588 ml., nearest is option C, 587 ml.

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Answer:

Lancelet

Explanation:

This is because a Lancelet is a small elongated marine invertebrate that lacks all of the physiological and biological traits of a leopard