what is the collection of protons and neutrons in the center of an atom called

Answer:

8.10 days  

Explanation:

The half-life of gold-198 (2.70 days) is the time it takes for half the gold to decay.  

After one half-life, half (50 %) of the original amount will remain.

After a second half-life, half of that amount (25 %) will remain, and so on.

We can construct a table:

No. of half-lives  Fraction remaining

            1                       [tex]\frac{1}{2}[/tex]  

            2                      [tex]\frac{1}{4}[/tex]

            3                     [tex]\frac{1}{8}[/tex]  

Thus, the gold will decay to ⅛ of its original mass after three half-lives.

∴ Time required = 3 × 2.70 days = 8.10 days

The exact time it would take for a 180 G sample of AU-198 to decay to 1/8 of its original mass depends on the half-life of AU-198, which isn't provided here. However, theoretically, it would take three half-lives for a substance to decay to 1/8 of its original mass.

The question is asking for the time it will take for a 180 G sample of AU-198 to decay to 1/8 it's original mass. AU-198 represents gold-198, which is a radioactive isotope of gold.

In radioactive decay problems, the time it takes for a substance to decay is dependent on the half-life of the substance. Without the specific half-life of AU-198 provided, we can only describe the general formula for calculating decay time.

The half-life of a radioactive isotope is the time it takes for half of the atoms in a sample to decay. This process is exponential, meaning after each half-life, half of the remaining atoms will decay.

To decay to 1/8 of the original mass, the substance has to go through 3 half-lives (since 1/2^3 = 1/8). So, the total time it would take for a sample to decay to 1/8 of its original mass would be 3 times the half-life of this isotope.

Once you obtain the half-life value of AU-198, simply multiply it by 3 to get the answer. Remember that the unit of your answer should be in the same unit as the half-life is given.

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T = final temperature  of the block

T₀ = initial temperature of the block = 23.4 °C

Q = energy lost  from the wooden block = - 759 J

c = specific heat capacity of wood = 1.716 J/(g  °C)

m = mass of the wooden block = 27.2 g

Heat lost from the block is given as

Q = m c (T - T₀)

inserting the values

- 759 = (27.2) (1.716) (T - 23.4)

T = 7.1 °C

The final temperature of a 27.2-gram wooden block is 7.1 °C. The correct option is A.

Temperature is the measurement of the hotness or coldness of the body. It is denoted by Kelvin.

By specific heat equation

[tex]Q = mc (T - T_\circ)[/tex]

where T = final temperature

T₀ is the initial temperature =23.4 °C

Q is lost energy from the block = - 759 J

c is specific heat = 1.716 joules/gram

m is the mass of the block = 27.2 g

Putting the values in the equation

[tex]\rm - 759 = (27.2) (1.716) (T - 23.4) = 7.1_\circ C[/tex]

Thus, the correct option is A is 7.1 °C.

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Thermal energy hopefully I can help you next time

Answer:

Thermal energy i think

Explanation:

Answer:

D. 0.044 m3

Explanation:

Air is not a compound because oxygen and nitrogen stay seperately in air instead of reacting nitric oxide which is toxic. Same thing apply to other gases. Of course there are also few compound inside the air. However, air you breathe in generally is mixture made up of different non reacting gases and gas compounds.

mark brainliest plssss

Answer: Air is a mixture

Explanation:

Mixture is a substance which has two or more components which do not combine chemically and do not have any fixed ratio in which they are present. Example: Air

Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions.Example: Carbon [tex](C)[/tex] , Oxygen [tex](O)[/tex]

Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: water [tex]CO_2[/tex]

Thus Air is a mixture as it is composed of various gases which are not chemically bonded.

The answer is d. extrusive.

The other term for it is igneous rock. Igneous rock is made in lava, and another term for igneous rock is extrusive rock.

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Answer:

The answer is Extrusive.

Explanation:

How I know is because I took the test and I got 100% this was one of the questions.

Answer:

Stars are made of gas.

Star color is related to temperature.

Explanation:

Stars are big ball of gases mainly hydrogen and helium. Stars can be bigger than sun or smaller. They appear as flat circles but are spheres. The brightness of star depends on their size and distance but not on their shape. Color of star is related to temperature. A blue color star is hotter than a yellow star. A red star is a cool star.

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Answer : The excess reactant in the combustion of methane in opem atmosphere is [tex]O_{2}[/tex] molecule.

Solution : Given,

Mass of methane = 23 g

Molar mass of methane = 16.04 g/mole

The Net balanced chemical reaction for combustion of methane is,

[tex]CH_4(g)+2O_2(g)\rightarrow CO_2(g)+2H_2O(g)[/tex]

First we have to calculate the moles of methane.

[tex]\text{ Moles of methane}=\frac{\text{ Given mass of methane}}{\text{ Molar mass of methane}}[/tex] = [tex]\frac{23g}{16.04g/mole}[/tex] = 1.434 moles

From the above chemical reaction, we conclude that

1 mole of methane react with the 2 moles of oxygen

and 1.434 moles of methane react to give [tex]\frac{2moles\times 1.434moles}{1moles}[/tex] moles of oxygen

The Moles of oxygen = 2.868 moles

Now we conclude that the moles of oxygen are more than the moles of methane.

Therefore, the excess reactant in the combustion of methane in open atmosphere is [tex]O_{2}[/tex] molecule.

Location the element zinc (Zn) on the periodic table:

Protons in an atom of Zn:  30

Electrons in a Zn atom: 30

Neutron in an atom of Zn: 35

Answer: Number of protons and electrons in Zinc are 30 and number of neutrons in zinc are 35.

Explanation:

Zinc is the 30th element of the periodic table having mass number of 65.

Atomic number = Number of protons = Number of electrons

For Zinc:

Z = 30

So, Number of protons = Number of electrons = 30

Mass number = Number of neutrons + Number of protons

A = 65

So, Number of neutrons = 65 - 30 = 35

Hence,  number of protons and electrons in Zinc are 30 and number of neutrons in zinc are 35.

I think the answer is B

The correct answer is option B which is fusion occurs in the sun.

Answer:

NaCI and H20

To simplify it.

Answer:

The products are NaCl and H₂O

Explanation:

The complete question is:

"Hydrochloric acid, or HCl, reacts with solid NaOH. What are the products of this chemical reaction?

HCl and NaCl

NaCl and H2O

NaOH and HCl

NaOH and H2O"

Neutralization reactions are the reactions between an acid and a base, producing salt and water. It is the type of reaction that happens in this case.

An acid and a base are strong when fully ionized, that is, in the ionization process they completely transform into positive cations or ions and negative anions or ions. So, a strong acid is an acid that completely dissociates into hydrogen ions and anions in solution.

In this case, both the HCl acid and the NaOH base are strong, completely dissociating as follows:

HCl → H⁺ + Cl⁻

NaOH → Na⁺ + OH⁻

So you have:

H⁺ + Cl⁻ + Na⁺ + OH⁻ → ?

The hydroxide anions and the hydrogen cations will neutralize each other to produce water.

H⁺ + OH⁻ → H₂O

So the sodium Na anions and Cl cations will form the NaCl salt.

Finally, the balanced chemical equation is

HCl + NaOH → NaCl +  H₂O

Unbalanced force acts on it

Answer:

Homeostasis is the maintenance of a stable internal environment despite changing external conditions.

Explanation:

In other words the answer is D. (:

Homeostasis is the maintenance of a stable internal environment despite changing external conditions. Thus option D is correct.

Homeostasis is the natural process of  cell response to its environment to remain as the steady state between internal conditions and outer environment.

In this process cell maintains temperature, fluid, sugar balance through it For Example when the outside climate is cold we start shivering and get energy from ATP to regulate our body temperature.

The primary components of homeostasis are  stimulus from a change in the environment, the receptor which react to the change by informing the control unit.

The control unit which communicates the change in the body, The effector receives the information and acts on the change.

Thus option D is correct.

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The answer to your question is,

C. Cloud of dust and gas in space.

-Mabel <3

a nebula is a  cloud of gas and dust in outer space, visible in the night sky either as an indistinct bright patch or as a dark silhouette against other luminous matter.

therfore your answer would be C  cloud of dust and gas in space

question answered by

(jacemorris04)

D: is the anwser that your looking for

Answer:

A variable or alteration to one part that affects an entire system

Explanation:

Answer:

Theory of spontaneous generation.

Explanation:

Spontaneous generation refers to an outdated body of thought on the ordinary formation of living organisms without descent from similar organisms. The theory of spontaneous generation held that living creatures could arise from nonliving matter and that such processes were common in place and regular

The volume of O2 gas  that is produced from  2.80 L of CO2 at STP is  1.40 L

write a balanced chemical equation

2Na2O2 + 2CO2 → 2Na2CO3 +O2

by use of mole ratio between CO2:O2 which is 2:1 the number of liters of O2 produced is therefore= 2.8 x 1/2 =1.40 Liters

Answer: The volume of [tex]O_2[/tex] produced will be 1.4 liters.

Explanation:

AT STP, the conditions are:

1 mole of a gas occupies 22.4 liters of volume.

The balanced chemical equation for the reaction follows:

[tex]2Na_2O_2+2CO_2\rightarrow 2Na_2CO_3+O_2[/tex]

By Stoichiometry of the reaction:

2 moles of carbon dioxide produces 1 mole of oxygen gas, which means that

44.8 liters of carbon dioxide gas produces 22.4 liters of oxygen gas.

So, 2.8 liters of carbon dioxide gas will produce = [tex]\frac{22.4}{44.8}\times 2.8=1.4liters[/tex] of oxygen gas.

Hence, the volume of [tex]O_2[/tex] produced will be 1.4 liters.

Explanation:

Water has a formula which represents two hydrogen atoms are attached to one oxygen atom. Therefore, the formula of water is [tex]H_{2}O[/tex].

Salt is also known as sodium chloride. Its formula represents that one sodium atom is attached to one chlorine atom, therefore, its formula is NaCl.

Carbon dioxide has a formula which represents one carbon atom is attached to two oxygen atoms. Therefore, its formula is [tex]CO_{2}[/tex].

Methane has a formula which represents one carbon atom is attached to four hydrogen atoms. Therefore, its formula is [tex]CH_{4}[/tex].

Thus, we can conclude that [tex]H_{2}O[/tex] is water, [tex]CO_{2}[/tex] is carbon dioxide, NaCl is salt, and [tex]CH_{4}[/tex] is methane.

The various compounds along with their corresponding formula would be as follows:

Water is made up of two atoms of hydrogen and an atom of oxygen bonded together as H2O.

Common salt consists of an atom each of sodium and chlorine bonded together as NaCl.

Carbon dioxide consists of an atom of carbon and two atoms of oxygen bonded together as CO2.

Methane consists of an atom of carbon and four atoms of hydrogen bonded together as CH4.

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Sample b 10 mL of water and sample c 20 mL of water have the same boiling point ,therefore option (b) and option (c) are correct .

The boiling point is defined as the temperature at which a liquid’s saturated vapor pressure equals the atmospheric pressure surrounding it.

The boiling point of water is the temperature at which the liquid water vapor pressure is equal to the pressure surrounding the body, and the body transforms into a vapor.

The boiling point is the temperature for a particular liquid to boil at.

For example, the boiling point for water, at a pressure of 1 a t m, is 100 degrees Celsius.

Sample b 10 mL of water and sample c 20 mL of water have the same boiling point ,hence option (b) and option (c) are correct .

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For the first one, you have to find one that has both a metal and a nonmetal in it, plus potassium. Bonds between nonmetals are called covalent because they share electrons and a bond between a metal and a nonmetal is an ionic bond because they exchange electrons.

Potassium chloride is KCl. Only an ionic bond.

Potassium hydride is KH. Only an ionic bond.

Potassium nitrate is KNO3. There we go, that has a covalent bond between the nitrogen and oxygen, and an ionic bond between potassium and the nitrogen and oxygen.

For the second one, potassium chloride is the answer because the other three also have covalent bonds. Chloride is the only one that isn't a compound.

Answer:

Potassium Nitrate, Potassium Chloride

Explanation:

Explanation:

Boiling point is defined as the temperature at which vapor pressure of liquid becomes equal to the atmospheric pressure.

When high temperature is provided to a liquid then forces of attraction between the molecules decreases and kinetic energy of its molecules increases. As a result, collision between the particles increases.

Also, it is known that kinetic energy is directly proportional to temperature. Therefore, when temperature increase kinetic energy also increases.

Hence, we can conclude that statements correctly describing water boiling in a pot are as follows.

Answer:

The water’s internal kinetic energy is increasing.

The water’s temperature is increasing.  

Individual water molecules are escaping.

(PLATO answer)

Answer is: 1p.

First energy level only have one sublevel 1s.

Second energy level has 2s and 2p, third has 3s, 3p and 3d and fourth has 4s, 4p, 4s and 4f.

Aufbau principle is a scheme used to reproduce the electron configurations of the ground states of atoms by successively filling subshells (orbitals) with electrons in a specific order.

Filling subshells in the following order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f.

The following which is not a possible sublevel is 1p. Thus option 1 is correct.

Electronic configuration is defined as a symbolic representation of the manner in which the electrons of its atoms are distributed over different atomic nuclei.

It can also be defined as distribution of electrons around the nucleus.

The general electronic configuration is

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p.....

Sublevel is defined as a level that is lower than or subordinate to another level.

Thus, the following which is not a possible sublevel is 1p. Thus option 1 is correct.

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Answer;

The above statement is true

upon heating a copper sample will expand, leading to a lower density

Explanation;

-The density of solids decreased with increase in temperature and vice versa. The increase in temperature causes the volume of the solid to increase which as a result decreases the density as Density=Mass/Volume. The temperature of a body is the average kinetic energy of the molecules present in it.

In other words; The temperature of a body is the average kinetic energy of the molecules present in it. Therefore; when heat is supplied ( or temperature is increased) the average kinetic energy increases which increases the volume and thus density decreases.

Helium- 2

Aluminum- 3

Fluorine- 7

Sodium- 1

Hope I helped.

The correct match of each element with its valence electron is as follows:

Valence electron is any of the electrons in the outermost shell of an atom capable of forming bonds with other atoms.

The number of valence electrons possessed by the atoms of an element determines the chemical reactivity of such element and it's groups on the periodic table.

According to this question, the appropriate valence electron has been assigned to each element based on their group on the periodic table.

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Answer: The density of a substance is 2 g/mL

Explanation:

To calculate the mass of solution, we use the equation:

[tex]\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}[/tex]

We are given:

Mass of a substance = 40 g

Volume of a substance = 20 mL

Putting values in above equation, we get:

[tex]\text{Density of a substance}=\frac{40g}{20mL}=2g/mL[/tex]

Hence, the density of a substance is 2 g/mL

The density of a substance that has a mass of 40g and a volume of 20mL is 2g/mL.

HOW TO CALCULATE DENSITY:

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