Radio waves bounce off of _____________ before returning to Earth

Answer:

A-Solid

Explanation:

Waves travel faster in solids & slowest in gases

This graph shows a straight line.

Answer:

The graph is a straight line that angles upward.

Answer:

A mixture of chlorine gas (Cl2) and fluorine gas (F2):

✔ London dispersion forces

Explanation:

Answer:

All the carbon atoms in the human body were created in the stars. Elementary particles, such as protons, were formed during the "big bang"; that amazing moment about 14 billion years ago in which the universe got it's start.

Some benefits of genetic engineering in agriculture are increased crop yields, reduced costs for food or drug production, reduced need for pesticides, enhanced nutrient composition and food quality, resistance to pests and disease, greater food security, and medical benefits to the world's growing population.

Insect resistance: Corn

Herbicide tolerance: Soybean

To balance a chemical equation you must pay attention that the algebraic equation has the same number of element atoms in reactant and the product.

A chemical equation is a term to refer to the symbolic description of a chemical reaction, that is, the written representation of symbols. For example:

The balance of an equation can be related to the law of conservation of matter, that is, the number of atoms of each element in the reactants is in the result.

Note: This question is incomplete, because the information some information is missing.

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The volume of sulphuric acid, H₂SO₄ needed for the complete reaction with 72.2 g of sodium hydroxide, NaOH is 5.31 L

We'll begin by calculating the number of mole in 72.2 g of NaOH. This can be obtained as follow:

Mass of NaOH = 72.2 g

Molar mass of NaOH = 23 + 16 + 1 = 40 g/mol

Mole = mass / molar mass

Mole of NaOH = 72.2 / 40

2NaOH + H₂SO₄ —> Na₂SO₄ + 2H₂O

From the balanced equation above,

2 moles of NaOH reacted with 1 mole of H₂SO₄.

Therefore,

1.805 mole of NaOH will react with = 1.805 / 2 = 0.9025 mole of H₂SO₄.

Mole of H₂SO₄ = 0.9025 mole

Molarity of H₂SO₄ = 0.170 M

Volume = mole / Molarity

Volume of H₂SO₄ = 0.9025 / 0.170

Thus, the volume of H₂SO₄ needed for the reaction is 5.31 L

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Answer:

Cell are the smallest life units on this planet

Explanation:

The following properties change across the periodic Table from group 1 to group 2

Group 1 are alkali metals that have one valence electron in the outermost orbit whereas alkaline earth metals are in group 2 have two valence electrons in the outermost orbit.

a) Ionic radius:

b) Ionisation enthalpy:

c) Density:

d) Melting point:

e) Electropositive character:

Thus, changes in properties are:

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Explanation:

Mixture is the physical Combination Of two or Substance

Example

a mixture of sugar and water.

Compound is the chemical combination of two or more metals.

Example.

a mixture of hydrogen and water.

A mixture of hydrogen and oxygen forms water or H2O

whereas The dihydrogen monoxide parody involves calling water by an unfamiliar chemical name, most often "dihydrogen monoxide" (DHMO), and listing some of water's properties in a particularly alarming manner, such as accelerating corrosion (rust) and causing suffocation (drowning). The parody often calls for dihydrogen monoxide to be banned, regulated, or labeled as dangerous. It plays into chemophobia and demonstrates how a lack of scientific literacy and an exaggerated analysis can lead to misplaced fears. The parody has been used with other chemical names such as hydrogen hydroxide, dihydrogen oxide, hydroxic acid, hydric acid and oxidane.

A Mixture of hydrogen and oxygen in varying concentrations can be sparked to produce water. This is formed due to the property of chemical combination.

A Mixture is the physical Combination Of two or Substance whereas a Compound is the chemical combination of two or more metals.

Example of a mixture is a mixture of sugar and water. And, Example of an compound is A mixture of hydrogen and oxygen forms water or H₂O

Water is also called as dihydrogen monoxide. The prefix mono and di are used to indicate a single atom and combination of two atoms respectively.   Some of its properties includes such as accelerating corrosion (rust) and causing suffocation (drowning).

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Answer:

ionic bond

Explanation:

Calcium gives its two valence electrons to oxygen and forms an ionic bond with oxygen. An ionic bond formed when one atom transfers one or more electrons from itself to its neighboring atom, and an ionic bond formed between the two atoms of the compound.

Entropy increases in reaction 1 due to increase in the number of particles while entropy decreases in reaction 2 due to decrease in the number of particles.

Entropy refers to the degree of disorderliness in a system. The higher the entropy, the more disorderly the system is and the lower the entropy, the less disorderly the system is. We must note that entropy increases with increase in the number of particles.

In the reaction,  2 KClO3 (s)⇌2 KCl (s)+3 O2 (g), entropy increases because one of the products is a gas and the number of particles increases from left to right. In the second reaction, CoCl2 (s)+6 H2O (g)⇌CoCl2⋅6H2O, entropy decreases because the number of particles decreases.

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Answer:

13.6 is the correct answer written in standard form.

Explanation:

1.36, move the decimal once to the right to get 13.6

Answer:

13.6

Explanation:

The standard form is 13.6

Answer:

First choice

Explanation:

Answer:

solution

Explanation:

solvent +solute =solution

This problem is describe the mole-ratio composition of an allow composed by tin, lead and cadmium. Ratios are given as Sn:Pb 2.73:1.00 and Pb:Cd is 1.78:1.00, and we are asked to calculate the mass percent compositon of Pb in the allow.

In this case, according to the given information, it turns out possible realize that the following number of moles are present in the alloy, according to the aforementioned ratios:

[tex]2.73mol Sn\\\\1.00molPb\\\\\frac{1.00molPb*1.00molCd}{1.78molPb}= 0.562molCd[/tex]

Next, we calculate the masses by using each metal's atomic mass:

[tex]m_{Sn}=2.73mol*\frac{118.7g}{1mol}=324.05g\\\\ m_{Pb}=1.00mol*\frac{207.2g}{1mol}=207.2g\\\\m_{Cd}=0.562mol*\frac{112.4g}{1mol}=63.2g[/tex]

Thus, the mass percent composition of each metal is shown below:

[tex]\%Sn=\frac{324.05g}{324.05g+207.2g+63.2g} *100\%=54.5\%\\\\\%Pb=\frac{207.2g}{324.05g+207.2g+63.2g} *100\%=34.9\%\\\\\%Cd=\frac{63.2}{324.05g+207.2g+63.2g} *100\%=10.6\%[/tex]

So that of lead is 34.9 %.

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The value of the work done in joule is 405.3 J.

We know that the work done is obtained using the relation;

w = PΔV

Where;

w = work done

P = pressure

V = volume

Now, substituting values,

w = 0.800( 15.0 -  10.0)

w = 4 atm L

Since;

1 L atm = 101.325 J

4 atm L  = 4 atm L × 101.325 J/1 L atm

= 405.3 J

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Answer:

Things like the age of the organism, the organism's diet, style of movement (walking or swimming) do not affect how it fossilizes. Answer 2: Fossilization happens when small chunks of rock (such as sand) enter the spaces in a body or plant that would have hosted resin, air, or soft tissue, preserving the body or plant

Answer:

Explanation:

Answer:

473 ml.

Explanation:

In gallons it’s equal to 0.125

Answer:

Neon 10,  mass: 20.18

Explanation:

Answer:

Noble gases

Explanation:

Noble gases are nonreactive, nonmetallic elements in group 18 of the periodic table. As you can see in the periodic table in the figure below, noble gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn).18 Jun 2021

Answer:

(b) matter is lost and energy is released

Explanation:

When atoms are being formed from its constituent components it weighs less this is called mass defect so the answer would be (b) matter is lost and energy is released.

Answer: so I was really scared to tell my mom and I was always thinking about how should I tell here but she should tell her mom an just said I think I started my thing  her mom wont get mad she got it to and every girl goes thru that so your not alone

Explanation; she does not have to tell her mom but her mom could helpo her and give her tips

Answer:

Tell her to calm down and tell her mum because her mom knows better and would be able to put her through better than anyone could have ever.

Answer:

0.86

Explanation:

1mol of Zn has mass of 65.39g.The amount of Zn is 2.5g65.39g/mol=0.038mol.

The amount of H2 produced is the same as the amount of Zn consumed (0.038mol).

1mol of ideal gas will occupy 22.4L at STP.

The H2 will occupy 0.038mol×22.4L/mol=0.86L

.

Answer:

1. An independent variable is manipulated, or changed. The dependent, or responding variable, changes based on the independent variable. The dependent variable is examined.

2. It is a controlled experiment.

Explanation:

In a controlled experiment all variables are kept the same, except for the one being tested, which is called the experimental variable , or independent variable . This group is the experimental group . The group that is not affected by the experimental variable is the control group .

Very often a graph will be used to analyze the results of the experiment. The independent/experimental variable is placed on the x-axis and the dependent variable is placed on the y-axis. The dependent variable is what is measured as a result of the application of the experimental variable.

A variable that is independent is altered. Based on the independent variable, the responding variable, or dependent variable, alters. Examining the dependent variable. The experiment is carefully controlled.

In mathematical modeling, statistical modeling, and experimental sciences, there are dependent and independent variables. Dependent variables get their name because, during an experiment, their values are investigated under the presumption or requirement that they are dependent on the values of other variables due to some law or rule.

A variable that is independent is precisely what it sounds like. It is a stand-alone variable that is unaffected by the other variables you are attempting to assess. Age, for instance, could be an independent variable.

When doing an experiment, the independent variable is what you alter, and the dependent variable is what changes as a result of that change. This is an easy way to conceive of independent and dependent variables.

Thus, based on the independent variable, the responding variable, or dependent variable, alters.

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Answer:

Step 1: Prepare for the project.

a) Read the entire Student Guide before you begin this project.

b) If anything is unclear, be sure to ask your teacher for assistance before you begin.

c) Gather the materials you will need to complete this project.

Step 2: Review the chemical reaction.

a) The chemical reaction that you will model is shown below. Calcium oxide (CaO) is a white

solid with a crystalline structure. It is made by heating limestone, coral, sea shells, or chalk,

which are composed mainly of calcium carbonate (CaCO3). During the heating process,

carbon dioxide (CO2) is released and calcium oxide (CaO) is produced. Commercially,

calcium oxide is called lime. One of the oldest uses of lime is to make mortar, a substance

used in construction to secure bricks, stones, and blocks together.

CaCO3  CaO + CO2

Step 3: Build a model of the reactant.

a) Use gumdrops and toothpicks to build a model of CaCO3.

b) Select one color of gumdrop for calcium, a second color for carbon, and a third color for

oxygen. Be sure to include a key of your chosen color scheme with your model.

c) Use the periodic table to help you determine the number of bonds each atom will form.

Step 4: Build models of the products.

a) Use gumdrops and toothpicks to build a model of CaO and a model of CO2.

b) Be sure to use the same colors of gumdrops for calcium, carbon, and oxygen as you did in

Step 3. Include a key of your chosen color scheme with your models.

c) Use the periodic table to help you determine the number of bonds each atom will form.

Step 5: Type one to two paragraphs that describe your models and explain the conservation of

mass in the chemical reaction.

a) Create a new blank document. Type your name at the top.

b) Type one to two paragraphs that describe your models and relate them to the law of

conservation of mass. Your document should:

i. identify the names of the reactants and products in the reaction.

ii. identify the number of molecules that make up the reactants and products.

iii. identify the type and number of atoms in each molecule of the reactants and products.

iv. explain what happens during the chemical reaction.

v. explain how mass is conserved during the chemical reaction.

Step 6: Evaluate your project using this checklist.

If you can check each criterion below, you are ready to submit your project.

 Did you create an accurate model of calcium carbonate (CaCO3)? Your model should include

the correct number of gumdrops for each element in calcium carbonate, consistent use of

colors for elements in calcium carbonate, and the correct number and placement of toothpicks

(bonds).

 Did you create an accurate model of calcium oxide (CaO)? Your model should include the

correct number of gumdrops for each element in calcium oxide, consistent use of colors for

elements in calcium oxide, and the correct number and placement of toothpicks (bonds).

 Did you create an accurate model of carbon dioxide (CO2)? Your model should include the

correct number of gumdrops for each element in carbon dioxide, consistent use of colors for

elements in carbon dioxide, and the correct number and placement of toothpicks (bonds).

Did you type one to two paragraphs that describe your models and relate them to the law of

conservation of mass? Your document should include the names of the reactants and

products in the reaction, the number of molecules that make up the reactants and products,

and the type and number of atoms in each molecule of the reactants and products. It should

also explain what happens during the chemical reaction and how mass is conserved during  the reaction

Step 7: Revise and submit your project.

a) If you were unable to check off all of the requirements on the checklist, go back and make  

b) When you have completed your project, submit your models to your teacher for grading.  

c) Submit your document through the virtual classroom. Be sure that your name is on it.

Step 8: Clean up your workspace.

a) Clean up your workspace. Return any extra materials to your teacher and throw away any  trash.

Explanation:

Answer:

Because oil have apolar molecules, while water have polar molecules

Answer:

Many chemical reactions are reversible; that is, the products of the reaction can combine to re-form the reactants. An example of a reversible reaction is that of hydrogen with iodine to form hydrogen iodide:

H2(g) + I2(g) 2 HI(g)

We can study this reversible reaction by placing hydrogen and iodine in a reaction vessel and then measuring the concentrations of H2, I2, and HI at various times after the reactants are mixed. Figure 13.8 is a plot of the concentrations of reactants and products of this reaction versus time. The concentration of hydrogen iodide increases very rapidly at first, then more slowly, and finally, after the time indicated by the vertical line marked "Equilibrium," remains constant. Similarly, the concentrations of hydrogen and iodine are large at the start of the reaction but decrease, rapidly at first, and then more slowly. Finally, they, too, become constant.

If this reaction were not reversible, the concentrations of hydrogen and iodine would have continued to decrease and the concentration of hydrogen iodide to increase. This process does not happen. Instead, as soon as any molecules of hydrogen iodide are formed, some decompose into hydrogen and iodine. Two reactions are taking place simultaneously: the formation of hydrogen iodide and its decomposition. When the concentrations of all these components become constant (at the equilibrium point in Figure 13.8), the rate of the forward reaction (H2 + I2 2 HI) must be equal to the rate of the reverse reaction (2 HI H2 + I2). A state of dynamic chemical equilibrium has then been reached, one in which two opposing reactions are proceeding at equal rates, with no net changes in concentration.

PICTURE 13.8

FIGURE 13.8 Concentration changes during the reversible reaction

H2(g) + I2(g) 2 HI as it proceeds toward equilibrium.

We have encountered this criterion for equilibrium before. In the equilibrium between a liquid and its vapor, the rate of vaporization is equal to the rate of condensation. In the equilibrium of a saturated solution with undissolved solute, the rate of dissolution is equal to the rate of precipitation. In the equilibrium of a weak acid with its ions, the rate of dissociation is equal to the rate of recombination. Note that none of these reactions is static: Two opposing changes are occurring at equal rates.

B. The Characteristics of Chemical Equilibrium

1. Equal rates

At equilibrium, the rate of the forward reaction is equal to the rate of the reverse reaction.

2. Constant concentrations

At equilibrium, the concentrations of the substances participating in the equilibrium are constant. Although individual reactant molecules may be reacting to form product molecules and individual product molecules may be reacting to re-form the reactants, the concentrations of the reactants and the products remain constant.

3. No free energy change

At equilibrium, the free energy change is zero. Neither the forward nor the reverse reaction is spontaneous and neither is favored. Consider the ice-water change. Above 0°C, ice melts spontaneously to form liquid water; G for this change is negative. Below 0°C, the change from ice to water is not spontaneous; G is positive. At 0°C, the two states are in equilibrium. The rate of melting is equal to the rate of freezing: the amount of ice and water and the amount of liquid water present remain constant, and the free energy change is zero as long as no energy is added to or subtracted from the mixture.

C. The Equilibrium Constant

In Chapter 12, we introduced the mathematical relationship between the concentrations of the components of an equilibrium, known as the equilibrium constant, Keq. We said that, for the general equation of a reversible reaction

Explanation:

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