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Answer:

12.02 g

Explanation:

From the question given above, the following data were obtained:

Half life (t½) = 2 days

Original amount (N₀) = 96 g

Time (t) = 6 days

Amount remaining (N) =..?

Next, we shall determine the rate of disintegration of the isotope. This can be obtained as follow:

Half life (t½) = 2 days

Decay constant (K) =?

K = 0.693 / t½

K = 0.693 / 2

K = 0.3465 /day

Therefore, the rate of disintegration of the isotope is 0.3465 /day.

Finally, we shall determine the amount of the isotope remaining after 6 days as follow:

Original amount (N₀) = 96 g

Time (t) = 6 days

Decay constant (K) = 0.3465 /day.

Amount remaining (N) =.?

Log (N₀/N) = kt / 2.303

Log (96/N) = (0.3465 × 6) / 2.303

Log (96/N) = 2.079/2.303

Log (96/N) = 0.9027

Take the anti log of 0.9027

96/N = anti log (0.9027)

96/N = 7.99

Cross multiply

96 = N × 7.99

Divide both side by 7.99

N = 96 /7.99

N = 12.02 g

Therefore, the amount of the isotope remaining after 6 days is 12.02 g

The challenges do scientists face in studying the sun is that due to high amount of heat, it is impossible to see sun.

Sun is a ball of hydrogen and helium gases which may produce large amount of heat as a result of nuclear fusion reaction.

High amount of heat is produced in the sun so it is not possible to see the sun from the normal eyes. Scientist uses telescope with mant filters to see a clear picture of the sun. Scientists are also not able to go near to the sun as produced heat is that much of power as they burn any object.

Hence above challenges are scientist face.

To know more about sun, visit the below link:

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Answer:

independent variable: a variable (often denoted by x ) whose variation does not depend on that of another.

dependent variable: a variable (often denoted by y ) whose value depends on that of another.

Explanation:

Answer: Salt is primarily composed of sodium chloride.

Explanation:

Answer:

just the second

Explanation:

Answer:

both are changes in state, and both conserve mass. Hope it helps and please have a good day or night

The amount of energy in joules : 4.31 x 10⁴ J

Energy can be interpreted as the ability to do work

There are several examples of energy , including heat energy

The amount of heat is influenced by the mass of the object and the difference in temperature

Can be formulated

Q = m.c.ΔT

Q: heat received or removed by an object (J)

m: object mass (kg)

c: heat type substance (J / kg⁰C)

ΔT: temperature change (⁰C)

The amount of energy given off is 1.03x10⁴ cal.

Because 1 cal= 4.184 J​, then

[tex]\tt =1.03\times 10^4\times 4.184\\\\=\boxed{\bold{4.31\times 10^4~J}}[/tex]

The correct Lewis Dot Structure for Nitrogen is structure C. Therefore, option C is correct.

The valence shell electrons in a molecule are depicted in an extremely simplified manner by a Lewis Structure. It is used to demonstrate how the electrons in a molecule are positioned around particular atoms.

Gilbert N. Lewis, who first described it in his 1916 article The Atom and the Molecule, gave the Lewis structure its name. Lewis structures add lines between atoms to represent shared pairs in a chemical bond, extending the idea of the electron dot diagram.

In Nitrogen molecule, every nitrogen atom has five valence electrons and there is a triple bond between the two nitrogen atoms. Thus, the correct lewis dot structure is; :N⋮⋮N: .

Thus, option C is correct.

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Answer:

Option D is correct.

H₂O + CO₂      →    H₂CO₃

Explanation:

First of all we will get to know what law of conservation of mass states.

According to this law, mass can neither be created nor destroyed in a chemical equation.

This law was given by French chemist  Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.

Example:

6CO₂ + 6H₂O + energy → C₆H₁₂O₆ + 6O₂

there are six carbon atoms, eighteen oxygen atoms and twelve hydrogen atoms on the both side of equation so this reaction followed the law of conservation of mass.

Now we will apply this law to given chemical equations:

A) H₂ + O₂   →    H₂O

There are two hydrogen and two oxygen atoms present on left side while on right side only one oxygen and two hydrogen atoms are present so mass in not conserved. This equation not follow the law of conservation of mass.

B) Mg + HCl   →   H₂ + MgCl₂

In this equation one Mg, one H and one Cl atoms are present on left side while on right side two hydrogen, one Mg and two chlorine atoms are present. This equation also not follow the law of conservation of mass.

C) KClO₃      →     KCl + O₂

There are one K, one Cl and three O atoms are present on left side of chemical equation while on right side one K one Cl and two oxygen atoms are present. This equation also not following the law of conservation of mass.

D)  H₂O + CO₂      →    H₂CO₃

There are two hydrogen, one carbon and three oxygen atoms are present on both side of equation thus, mass remain conserved. Thus is correct option.

The chemical reaction that follows the conservation of mass has been the formation of hydrogen carbonate. Thus, option D is correct.

The conservation of mass states that the mass of the reactant and products has been equal. The mass can be calculated in terms of the number of atoms.

(A) [tex]\rm H_2\;+\;O_2\;\rightarrow\;H_2O[/tex]

The number of atoms of Hydrogen:

Reactant = 2

Product = 2

The number of atoms of Oxygen:

Reactant = 2

Product = 1

The number of atoms of products and reactant is not equal, Thus, the reaction did not follow the conservation of mass.

(B) [tex]\rm Mg\;+\;HCl\;\rightarrow\;H_2\;+\;MgCl_2[/tex]

The number of atoms of Mg:

Reactant = 1

Product = 1

The number of atoms of H:

Reactant = 1

Product = 2

The number of atoms of Cl:

Reactant = 1

Product = 2

The number of atoms of products and reactant is not equal, Thus, the reaction did not follow the conservation of mass.

(C) [tex]\rm KClO_3\;\rightarrow\;KCl\;+\;O_2[/tex]

The number of atoms of K:

Reactant = 1

Product = 1

The number of atoms of Cl:

Reactant = 1

Product = 1

The number of atoms of O:

Reactant = 3

Product = 2

The number of atoms of products and reactant is not equal, Thus, the reaction did not follow the conservation of mass.

(D) [tex]\rm H_2O\;+\;CO_2\;\rightarrow\;H_2CO_3[/tex]

The number of atoms of H:

Reactant = 2

Product = 2

The number of atoms of O:

Reactant = 3

Product = 3

The number of atoms of C:

Reactant = 1

Product = 1

The number of atoms of products and reactant is equal, Thus, the reaction follows the conservation of mass.

The chemical reaction that follows the conservation of mass has been the formation of hydrogen carbonate. Thus, option D is correct.

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Answer:

190.4 g

Explanation:

To obtain the mass of the object, we must be able to obtain the reading of the triple beam balance.

Thus, the reading of the balance can be obtained by simply adding the various values as indicated by the pointer in each scale.

This can be obtained as follow:

Scale 1 = 90 g

Scale 2 = 100 g

Scale 3 = 0.4 g

Reading of the balance = Scale 1 + Scale 2 + Scale 3

Reading of the balance = 90 + 100 + 0.4

Reading of the balance = 190.4 g

Thus, the mass of the object as indicated by the triple beam balance is 190.4 g.

Answer:

V = l * w * h

V = 150.00 mm x 1cm/10 mm x 10.00 cm x 0.95 m x 100 cm/1 m = 1.4 x 104 cm3 D = M/V

M = D * V = 19.3 g/cm^3 * 1.4 * 104 cm^3 = 2.7 x 10^5 g = 270000 grams

Answer:

The mass is 12.0107 but it rounds up to 12

Answer: la masa porque a lo largo del tiempo se fueron creando planetas por todo el universo

Explanation:

Answer:

The volume of the gas at 200 mmHg will be 2 L.

Explanation:

As the volume increases, the gas particles (atoms or molecules) take longer to reach the walls of the container and therefore collide with them fewer times per unit of time. This means that the pressure will be lower because it represents the frequency of collisions of the gas against the walls. In this way pressure and volume are related, determining Boyle's law which says:

"The volume occupied by a certain gaseous mass at constant temperature is inversely proportional to pressure"

Boyle's law is expressed mathematically as:

P * V = k

Now it is possible to assume that you have a certain volume of gas V1 that is at a pressure P1 at the beginning of the experiment. If you vary the volume of gas to a new value V2, then the pressure will change to P2, and it will be fulfilled:

P1 * V1 = P2 * V2

In this case:

Replacing:

800 mmHg* 500 mL= 200 mmHg* V2

Solving:

[tex]V2=\frac{800 mmHg* 500 mL}{200 mmHg}[/tex]

V2= 2,000 mL= 2 L (being 1,000 mL=1 L)

The volume of the gas at 200 mmHg will be 2 L.

Answer:

Explanation:

The atomic number (number at the top) is the amount of protons and the amount of electrons. So if an element has an atomic number of 5, you know that it has 5 protons and 5 electrons. The atomic mass (number at the bottom) is the amount of protons and neutrons added together.

Answer:

Please find attached a sketch of the heating curve of water at atmospheric pressure ( approximately 101 kPa) as traced from an online source

Explanation:

Given that the pressure at 101 kPa is approximately 1 atmosphere, we have;

The melting point and the boiling point occurs at approximately 0°C and approximately 100°C, respectively;

The melting point and the boiling point experience latent heat, therefore that temperature remains the same, though heat is continuously added

Also, given that the latent heat of vaporization (22.6 × 10⁵ J/kg) is approximately 7 times the latent heat of fusion is (3.33 × 10⁵ J/kg), the length of the plateau representing evaporation would be approximately 7 times longer than the length representing fusion.

The heating curve obtained from an online source for water at atmospheric pressure, is presented in the attached sketch.

Answer:

0.123 M

Explanation:

Molarity, which is molar concentration can be calculated by using the formula;

Molarity = number of moles (n) / Volume (V)

Number of moles of NH4NO3 can be calculated by using;

Mole = mass (M) / Molar mass (MM)

Since atomic mass of N= 14, H=1, O=16

Molar mass of NH4NO3 = 14 + 1(4) + 14 + 16(3)

= 14 + 4 + 14 + 48

= 80g/mol

1 pounds = 454g

2.13 pounds= 2.13 × 454 g

= 967.02g

Hence; mole of NH4NO3 = 967.02/80

= 12.09moles

Molarity of NH4NO3 in water (solution) = number of moles of NH4NO3 ÷ volume of water

1 gallon = 3.79Litres

26gallons = 26 × 3.79 litres

= 98.54 Litres

Therefore, Molarity = 12.09/98.54

Molarity of NH4NO3 solution = 0.1226

= 0.123M or mol/L

Answer:

Explanation:

The density of a substance can be found by using the formula

[tex]density = \frac{mass}{volume}\\[/tex]

From the question

mass = 8.32 g

volume = 4.3 mL

So we have

[tex]density = \frac{8.32}{4.3} \\ = 1.934883720...[/tex]

We have the final answer as

Hope this helps you

d. 3

Explanation:

because the valence electrons on O is 3

carbon monoxide: CO

water:H2O

salt:NaCl

copper: Cu

Answer:

The element will be [tex]^{161}_{80}X[/tex]

Explanation:

Given that,

Number of proton = 80

Number of neutron = 81

Number of electron = 79

We know that,

The atomic number is equal to the number of proton.

So, the atomic number is 80.

According to atomic number,

The element will be mercury.

We need to calculate the atomic mass

Using formula of atomic mass

[tex]atomic\ mass=atomic\ number+number\ of\ neutron[/tex]

Put the value into the formula

[tex]atomic\ mass=80+81[/tex]

[tex]atomic\ mass=161[/tex]

We need to find the element

Using atomic mass and atomic number

[tex]atomic\ mass\ number A=161[/tex]

[tex]atomic\ number Z=80[/tex]

So, the element will be

[tex]^{A}_{Z}X[/tex]

Put the value of A and Z

Hence, The element will be [tex]^{161}_{80}X[/tex]

Answer:

145 hours

Explanation:

Since one hour of riding a bicycle takes up 505 kcal of energy. It is also stated that one gram of body fat is equal to 7.70 kcal. Also, it is given that 1 pound of body fat is equal to 454 g.

Hence;

1 Ib= 454 g

21 Ib= 21 × 454/1 = 9534 g

But

1g of body fat = 7.70kcal

9534 g of body fat = 9534 × 7.70 kcal/1 = 73411.8 kcal

If 505 kcal is lost in 1 hour

73411.8 kcal is lost in 73411.8 kcal × 1hour/505k cal = 145 hours

Answer:

Height of tray

Explanation:

The question is incomplete, the complete question is;

One tank of goldfish is feed the normal amount which is once a day, a second tank is fed twice a day, and a third tank is fed four times a day during a 6 week study. The fishes' body fat is recorded daily.

Independent Variable-

Dependent Variable-

Constants

Control Group-

Answer:

A) The amount of food the gold fish receives

B) Body fat of the gold fish

C) -Type of fish used in the study (gold fish)

Time period within which the fishes were fed (Six week period)

Shape and size of tank

D) group of gold fish fed the normal amount

Explanation:

The purpose of the study is to determined the impact of amount of feed on the body fat of gold fish. Hence, the amount of feed is the independent variable while the body fat of the feed is the dependent variable.

The control group receives the normal amount of feed (once a day). The fishes are all gold fish, fed within a six week period. All the tanks were of the same shape and size. These are the constants in the study.

Answer:

2.7 moles of neon contain 16.3 × 10²³ atoms of neon.

Explanation:

Given data:

Number of moles of neon = 2.7 mol

Number of atoms of neon = ?

Solution:

We will use using Avogadro number to solve given problem.

"It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance"

The number 6.022 × 10²³ is called Avogadro number.

1 mole of neon = 6.022 × 10²³ atoms of neon

2.7 mole of neon × 6.022 × 10²³ atoms of neon / 1 mole of neon

16.3 × 10²³ atoms of neon

Thus, 2.7 moles of neon contain 16.3 × 10²³ atoms of neon.

Answer:

Kinetic energy + Potential energy

Answer:

The volume of container is 39.14 L.

Explanation:

Given data:

Number of moles of neon = 4.0 mol

Pressure of gas = 2.5 atm

Temperature of gas = 25°C

Volume of container = ?

Solution:

we will use general gas equation,

PV = nRT

P= Pressure

V = volume

n = number of moles

R = general gas constant = 0.0821 atm.L/ mol.K  

T = temperature in kelvin

Now we will convert the temperature.

25+273 = 298 K

Now we will put the values in formula.

2.5 atm × V = 4.0 mol × 0.0821 atm.L/ mol.K ×  298 K

V = 97.86 atm.L /2.5 atm

V = 39.14 L

The volume of container is 39.14 L.

Answer:

8368 Joules

Explanation:

Answer:

Calcium cyanamide

Explanation:

I think it has to be calcium cyanide, because of the cyanamide ion (CN).

Explanation:

(1) heavier materials sink to the bottom of the mixture

(2)use a filter funnel and filter paper (filtration method)

(3) ferromagnetic materials (typically metals)

The quote; “Heisenberg may have slept here.” is used to show a situation that involves uncertainty.

The quote; “Heisenberg may have slept here.” is used to connote uncertainty. Recall that Heisenberg the German scientist is the famous inventor of the uncertainty principle.

Hence, the quote; “Heisenberg may have slept here.” is used to show a situation that involves uncertainty.

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