Can you help me please

Answer:

A. 28 years

Explanation:

Applying,

R = R'(2ᵃ/ⁿ).............. Equation 1

Where R = Original sample, R' = Sample left after decay, a = Total time taken to decay, n = half life.

From the question,

Given: R = 12 g, R' = 6 g, a = 28 years.

Substitute into equation 1 and solve for n

12 = 6(2²⁸/ⁿ)

12/6 = 2²⁸/ⁿ

2²⁸/ⁿ = 2

Equation the base,

28/n = 1

n = 28 years.

Hence the half-life is 28 years

Answer:

3. The limiting reactant is the reactant that gives you the smaller amount of product. Therefore HCI is the limiting reactant in this problem. In this reaction 9.4 grams of ZnCl2 will form and there will be leftover zinc that did not react.

Taking into account the definition of molarity,  the molarity of a solution made up of 15.5 mol of ammonium sulfate dissolved in enough water to make 45 liters of solution is 0.34 moles/L.

The molar concentration is a measure of the concentration of a solute in a solution, be it some molecular, ionic or atomic species and indicates the number of moles of solute contained in one liter of solution.

The molarity of a solution is calculated by:

molarity= number of moles÷ volume

Molarity is expressed in units moles/L.

In this case, you have:

Replacing in the definition of molarity:

molarity= 15.5 moles÷ 45 L

Solving:

molarity= 0.34 moles/L

Finally, the molarity of the solution is 0.34 moles/L.

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Answer:

I believe the answer would be C4H9O2.

Answer:

Explanation:

Mass the fluid, find its volume, and divide mass by volume. To mass the fluid, weigh it in a container, pour it out, weigh the empty container, and subtract the mass of the empty container from the full container. To find the volume of the fluid, you simply measure it very carefully in a graduated cylinder.

"A boy sits in a chair and the floor pushes the boy" is not an action-reaction pair according to Newton's third law of motion.

According to Newton's third law of motion, every action which occurs in nature has an equal as well as opposite reaction. If a particular object Z happens to exert a force on another object Y then the object Y will also exert an equal as well as opposite force on object Z.
For example, when an oar pushes the water, the water also pushes the oar; when a dog wags its tail, the tail also wags the dog and when a missile pushes gas out, the gas also pushes the missile forward. All these instances involve an action-reaction pair.

Hence, option d. "a boy sits in a chair, and the floor pushes the boy" is the correct option.

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In a car engine, energy in the fuel's chemical energy stores is transferred to useful kinetic energy stores.

Explanation:

Chemical energy is the form of energy held within the fuel. A car's engine operates by burning fuel. The fuel is burned, creating mechanical energy that moves the vehicle. The engine thus transforms chemical energy into mechanical energy.

By applying pressure to the pistons and exerting work on them, the internal combustion engine of a car transforms the potential chemical energy in gasoline and oxygen into thermal energy, which is then translated into mechanical energy that drives the vehicle (raising its kinetic energy).

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Explanation:

The lunar phase or Moon phase is the shape of the Moon's directly sunlit portion as viewed from Earth. The lunar phases gradually change over a synodic month as the Moon's orbital positions around Earth and Earth around the Sun shift.

The answer to the given operations with proper number of significant figures is 5.7 × 10².

Significant figures or numbers can be defined as those particular numbers or digits which are essential in determining the accuracy of a particular value. For example, 4.392 has 4 significant figures.

When we are rounding off a number to write it with the proper number of significant figures, we first need to decide the amount of significant figures that it should have.

On calculating the given operation,

⇒ 108 × 5.3 = 572.4

In significant figures,

= 5.72 × 10²

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4-methyl-2-pentene s the expected major organic product from treatment of 4-methyl-2-pentyne with sodium metal in liquid ammonia.

The process includes hydrogenation of an alkyne to an alkene in liquid ammonia using sodium metal. This is a particular reaction that leads in the creation of trans alkene.  Alkynes are hydrocarbons with triple carbon-carbon bonds. For molecules with a single triple bond, their typical formula is CnH2n-2 (and no rings).

A number of the same reactions occur in alkynes as in alkenes, but they can react twice due to the existence of two p-bonds inside the triple bond. When sodium dissolves into liquid ammonia (boiling point -33 °C), it turns a vivid blue. When there are alkynes present, they have reduced to a trans (i.e. E) alkene.

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Irony is a mismatch between what is expected and what actually occurs. These literary methods aid in the creation of dramatic effects in writing.

Irony is a disconnect between what is expected to happen and what actually happens. These types of literary devices help in creating a dramatic effect in literature.

Irony is a literary device which was used extensively in Greek tragedy. It involves expressing the meaning of something by making use of words which technically mean the opposite of the original thing being conveyed.

Irony is used for a dramatic or humorous effect.  There are three types of irony seen in literature as follows:

• Verbal Irony  

• Situational Irony  

• Dramatic Irony  

Verbal irony involves the usage of different words to mean something dissimilar to what they look like they actually mean.  

Situational Irony means that what happens is totally different from what was expected to be happening.

Dramatic Irony occurs in plays, etc. where the audience or the readers are more aware of what is actually going on as compared to the character in the scene.

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Both concentration and conductivity increase when larger amounts of sugar in a beaker of water dissolves.

The volume of the resulting solution will be larger than one quart if you dissolve a cup of sugar in a quart of water. In comparison to distilled water, the concentration of solutes inside the cell is higher. Most of the time, a particular amount of solvent can only dissolve a specific maximum amount of solute. This maximum amount is specified as the solubility of the solute. Only solutions with charge carriers will be able to conduct electricity. Simply having polar molecules in the solution is insufficient. It must be able to transfer electrons between points with the least amount of interference.

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ΔHrxn∘ = -144 kj / mol is the Standard Enthalpy of the reaction.  It is the sum of the individual enthalpies of the reactants subtracted from the sum of enthalpies of the products.  

2CuO(s)+NO(g) → Cu2O(s)+NO2(g)

[tex]Cu_{2}O[/tex] → 2[tex]Cu[/tex]  +  1/2 [tex]O_{2}[/tex]                                                        eqn 1

ΔH1 =  [tex]Cu_{2}O[/tex]  -  2 Cu - 1/2 [tex]O_{2}[/tex]

ΔH1 = -168.6 kj / mol  

2[tex]NO[/tex] + [tex]O_{2}[/tex] → [tex]2NO_{2}[/tex]                                                              eqn 2

ΔH2 = 2 [tex]NO[/tex]  +  [tex]O_{2}[/tex]   -  [tex]2NO_{2}[/tex]

ΔH2 = -114.1 kj / mol  

[tex]CuO[/tex] → [tex]Cu[/tex]  +  [tex]1/2 O_{2}[/tex]                                                            eqn 3

ΔH3 = Cuo - Cu -  [tex]1/2 O_{2}[/tex]

ΔH3=  157.3 kj / mol  

1/2 eqn 2    +          2  eqn 3    -  eqn 1

Δ H= -57.05 + 78.65 -168.6

ΔH= -144 kj / mol

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Answer:

Water is a compound because it is made up of water molecules. There is no such thing as water atoms. Water molecules are made of hydrogen and oxygen atoms, in the definite proportion of two hydrogens for one oxygen.

Explanation:

The difference between a molecule and a compound is this:

A molecule consists of two or more atoms joined by a chemical bond.

A compound consists of two or more different atoms joined by chemical bonds.

Water (H2O) is both a molecule and a compound.

Hydrogen gas (H2) and oxygen gas (O2) are molecules but because the atoms of which they are made are not different, they do not qualify as compounds.

Answer:

This is what I put, it hasn't been graded though...

Within the system, the energy is flowing from your hand to the ice cream cone. Energy is also flowing from the surroundings to the ice cream cone unless it's reeeeaally cold in the surroundings in which case why are you even holding an ice cream cone when it's that cold?

Answer:

1935J

Explanation:

Answer:

[tex]\boxed {\boxed {\sf C. \ 1935 \ J}}[/tex]

Explanation:

The equation for this problem is:

[tex]q=mc\Delta T[/tex]

where m is the mass, c is the specific heat capacity, and ΔT is the change in temperature.

The mass is 3 kilograms, but the specific heat capacity includes grams in the units. Convert kilograms to grams. There are 1000 grams in 1 kilogram.

The specific heat capacity for lead is found on the table. It is 0.129 J/g°C.

Let's find the change in temperature. It is raised from 15 °C to 20 °C.

Now we know every value.

Substitute the values into the formula.

[tex]q= (3000 \ g)( 0.129 \ J/g \textdegree C)(5 \textdegree C)[/tex]

Multiply the first 2 numbers together. The units of grams cancel.

[tex]q= (387 \ J/ \textdegree C )(5 \textdegree C)[/tex]

Multiply again. This time the units of degrees Celsius cancel.

[tex]q= 1935 \ J[/tex]

1935 Joules of energy are required and choice C is correct.

Give a succinct description of how the various alkene reactants were combined to create the same result. The most stable intermediate carbocation will arise as a result of an electrophilic proton addition in the reaction between HCl and both alkenes.

The observed product is produced in both cases by adding Cl- to the tertiary carbocation that is produced. By figuring out the physical properties of the reactants and products, negative entropy in chemical processes may also be calculated. Gas molecules are widely spaced apart and move randomly in all directions, which results in high entropy in gases. Being a liquid converting into a solid, water freezing into ice is an entropy-reducing process. Due to the molecules' reduced freedom of movement, a solid has less chaos. A negative entropy reaction occurs when hydrogen and oxygen combine to generate water.

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Answer:

b. 23.3g

Explanation:

Based on the reaction:

CH₄ + 2O₂ → CO₂ + 2H₂O

To find the mass of CO2 produced we must find, as first, the limiting reactant. With limiting reactant we can find the moles and the mass of CO2 as follows:

Limiting reactant:

For a complete reaction of 0.53 moles of CH4 are necessaries:

0.53 moles CH4 * (2mol O2 / 1mol CH4) = 1.06 moles O2.

As there are 1.5 moles, CH4 is limiting reactant.

Moles CO2:

1 mole of CH4 produce 1 mole of CO2. That means the moles of CO2 formed are 0.53 moles.

Mass CO2 (Molar mass: 44.01g/mol)

0.53 moles CO2 * (44.01g / mol) =

b. 23.3g

Answer: D!! ( difference in the potential energy of the reactants and products )

Explanation:

i have the same test

Answer:

OH^-

Explanation:

Any substance that is able to neutralize acidity in the stomach is generally known as an antacid. There are various kinds of antacids that are in common use. It should be noted that the stomach is usually slightly acidic.

Milk of magnesia is the substance magnesium hydroxide with chemical formula Mg(OH)2. A solution of milk of magnesia contains Mg^2+ and OH^-.

Hence the negative ion contained in milk of magnesia is the hydroxide ion  OH^-.

Answer:

The energy should be high.

Explanation:

Bonds do store energy and release it depending if it's endothermic or exothermic. The energy should be low because when a bond forms (endothermic) it releases heat, which helps form bonds. Having a high energy means the bond is absorbing energy, which helps break bonds (endothermic). How this helps!

According to the question,16.2 kPa is equal to 0.16 atmospheres.

What is the atmospheres?

The atmosphere is the thin layer of gases and particles that surrounds Earth, protecting us from the sun’s harmful radiation and maintaining the planet’s temperature. It is composed of 78% nitrogen, 21% oxygen, 0.9% argon, 0.03% carbon dioxide, and trace amounts of other gases, as well as water vapour, dust, and other particles. The atmosphere works by trapping heat from the sun, allowing temperatures to remain relatively stable throughout the world. It also helps regulate the water cycle, ensuring that water remains available for life on Earth. The atmosphere also helps protect us from environmental hazards like ozone depletion and acid rain. In addition, it is home to many species of birds, insects, and other animals. Without the atmosphere, Earth would be a barren, lifeless planet.

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Answer:

3KClO4 + KCl ➡️ 4KClO3

2AlI3 + 3HgCl2 ➡️ 2AlCl3 + 3HgI2

nitric acid (HNO3) is classified as a strong acid in water, which means that it dissociates completely in water to produce hydrogen ions (H+) and nitrate ions (NO3-).

This is in contrast to weak acids, which only partially dissociate in water. Strong acids have a very low pH (typically less than 1) and are highly corrosive, making them useful for many industrial applications such as making fertilizers, explosives, and dyes. However, they can also be dangerous and must be handled with care. A strong acid is an acid that fully dissociates or ionizes in water, meaning it releases all of its hydrogen ions (H+) into solution. This makes the acid highly acidic and gives it a low pH (typically less than 1). Some examples of strong acids include hydrochloric acid (HCl), sulfuric acid (H2SO4), nitric acid (HNO3), and perchloric acid (HClO4). Strong acids are highly reactive and can cause chemical burns and other damage if not handled properly. \

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The volume of the copper is equal to  4cm³.

The density of the substance can be described as the substance's mass per unit of its volume. The symbol commonly used to express density is ρ and the D letter can also be used.

The mathematical formula of the density can be expressed as written below:

Density = Mass/Volume or ρ = m/V

The density of a material varies with temperature and pressure. There is a small variation for solids as well as liquids but much larger for gases. Increasing the pressure of material decreases the volume of material and thus increases its density.

Given the mass of the copper = 35.2 g

The density of the copper at  20°C, d = 8.80 g/cm³

The volume of the copper, V = mass/density = 35.2/8.80 = 4 cm³

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The pressure acting here is 3.32 atm. Then the volume of copper can be determined using ideal gas law. The volume is 3.9 L.

Ideal gas equation is a combination of   Boyle's law, Charle's law and Avogadro's law. The expression relating pressure, volume,   temperature and number of moles of a gas is written as:

PV = nRT.

It can be rearranged as PM = dRT.

where d is the density and M be the mass.

Atomic mass of copper = 63.5 g/mol

density = 8.80 g/cm³

T = 20° C or 293 K.

Then pressure p =  dRT/M

p = 8.80 g/cm³ × 0.082× 293 /63.5 = 3.32 atm

Now the weight of copper = 35.2 g

number of moles of Cu = 35.2/63.5 = 0.5 g.

Then, v = nRT/P

v = 0.5 × 0.082 × 293 /3.32 = 3.9 cm³.

Therefore, the volume of copper is 3.9 L.

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When 200 grams of water cools from 50.0°C to 250°C, the total amount of heat energy released by the water is The total amount of energy released is 20, 930 J.

We will apply the formula. q = mCt, where q is the amount of heat energy released. m= mass. C is the specific heat of the water. T= temperature change. Because the specific heat of the water has not been specified, we will use the standard value of 4.186J/g °C. q = mCΔT. q = 200 × 4.186 × (50 -25) (50 -25) q = 200 × 4.186 × 25 q = 5000 × 4.186 q = 20, 930 The total amount of energy released is 20, 930 J.

In physics, energy (from Ancient Greek: v, enérgeia, "activity") is a quantitative property that is transferred to a body or a physical system and is visible in the performance of work as well as in the form of heat and light. Energy is a conserved quantity, which means that it can be converted in form but not created or destroyed. The joule is the SI unit of energy measurement (J).

The kinetic energy of a moving object, the potential energy stored by an object (for example, due to its position in a field), the elastic energy stored in a solid object, and the chemical energy associated with chemical reactions are all common types of energy.

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Answer:

B.  Mg3N2

Explanation:

There are 20.0 grams total material (14.4g Mg and 5.6 g N).  We can convert grams into moles of each element by dividing by that element's molar mass (g/mole) to yield the number of moles of each element.  To find the empirical formula, we need to convert the moles of each to a whole number by using a fracor that provides a whole number for each element.  5 works well, and we get 0.6x5 = 3 Mg atoms and 0.4x5 = 2 N atoms.

Mass % g/mole grams moles       Factor of 5

Mg 72.00% 24.305 14.4         0.6             2.962 or 3

N 28.00% 14.007 5.6         0.4             1.999  or 2  

100.0%          20          1.0      

There are 3 Mg and 2 N atoms per molecule.  The empirical formula is Mg3N2.

According to the data collected during the experimental reaction in the laboratory, and the balanced equation of the reaction, 5 moles of iron (Fe) and 2.5 moles of aluminum oxide (Fe2O3) were produced.

Fe2O3 + 2Al → 2Fe + Al2O3

If 1 mole of Fe2O3 is combined with 2 moles of Al

So 3 moles of Fe2O3 combine with x moles of Al

X moles of Al = 3 moles Fe2O3 x 2 moles Al / 1 mole Fe2O3 = 6 moles

Limiting reagent: Al, because there are only 5 moles available

If 2 moles of Al produce 2 moles of Fe

So 5 moles of Al produce x moles of Fe

X moles of Fe = 5 moles of Al x 2 moles of Fe / 2 moles of Al = 5 moles

If 2 moles of Al produce 1 mole of Fe2O3

So 5 moles of Al produce x moles of Fe2O3

X moles of Fe = 5 moles of Al x 1 mole of Fe2O3 / 2 moles of Al = 2.5 moles

By establishing the balanced equation of the reaction and the stoichiometric relationships, the amount of limit reagent is first determined and with this data, the moles of products are later determined.

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The amount of energy used to heat the water from 0°C to 70°C is 8,786.4J.

The amount of energy used in heating a substance can be calculated using the following formula:

Q = mc∆T

Where;

According to this question, a student heated 30 milliliters of water from 0 degrees celsius to 70 degrees celsius.

Since 1mL of pure water equals 1 gram, then 30mL of water will equal 30grams of water.

Q = 30 × 4.184 × (70 - 0)

Q = 8,786.4J

Therefore, 8,786.4J is the energy used to heat the water sample.

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