Which of these best describes a scientific law?

• a rule made by a government

• a rule that does not depend on observable evidence

• a statement which varies under the same conditions

• a statement about how things act in the natural world

Answer:

A. Nucleus

Nucleus is the answe

Answer:

1)2kclo3=2kcl+3o2

2)2NaCl+F2=2NaF+cl2

3)Pb(OH)2+2HCl=2H2O+PbCl2

4)2Albr3+3k2so4=6kbr+al2(so4)3

5)CH4+2O2=CO2+2H2O

Explanation:

1)

2Fe+3Cl2 →2FeCl3

2)

CH4+2O2 → CO2 +2H2O

3)

SnO2+2H2 →2H2O +Sn

4)

2KOH + H2SO4 → K2SO4+2H2O

Answer:

68.6 °C

Explanation:

From conservation of energy, the heat lost by acetone, Q = heat gained by aluminum, Q'

Q = Q'

Q = mL where Q = latent heat of vaporization of acetone, m = mass of acetone = 3.33 g and L = specific latent heat of vaporization of acetone = 518 J/g

Q' = m'c(θ₂ - θ₁) where m' = mass of aluminum = 44.0 g, c = specific heat capacity of aluminum = 0.9 J/g°C, θ₁ = initial temperature of aluminum = 25°C and θ₂ = final temperature of aluminum = unknown

So, mL = m'c(θ₂ - θ₁)

θ₂ - θ₁ = mL/m'c

θ₂ = mL/m'c + θ₁

substituting the values of the variables into the equation, we have

θ₂ = 3.33 g × 518 J/g/(44.0 g × 0.9 J/g°C) + 25 °C

θ₂ = 1724.94 J/(39.6 J/°C) + 25 °C

θ₂ = 43.56 °C + 25 °C

θ₂ = 68.56 °C

θ₂ ≅ 68.6 °C

So, the final temperature (in °C) of the metal block is 68.6 °C.

The final temperature of the metal block is 74.97°C

The specific heat of a substance is the required quantity of heat needed to raise the temperature of 1 gram of the substance by 1° C.

From the parameters given:

The number of moles of acetone is:

[tex]\mathbf{= 3.33 g \times \dfrac{mol}{58.08 \ mol}}[/tex]

= 0.0573 mol

At standard conditions, the heat of vaporization of acetone is:

[tex]\mathbf{\Delta H = 32.0 \ kJ/mol \times 0.0578 \ mol } \\ \\ \mathbf{\Delta H = 1.8496 \ kJ } \\ \\ \mathbf{ \Delta H = 1.85 \times 10^3 \ J}[/tex]

Given that:

The specific heat of the aluminum is = 0.903 J/g° C

The heat energy can be computed as:

q = msΔT

q = 41 g × 0.903 J/g° C × (x - 25°C)

Using the calorimetry principle, heat energy lost by metal = heat energy gained by acetone.

i.e.

[tex]\mathbf{q_{(acetone)} gain = q_{(metal)} lost }[/tex]

[tex]\mathbf{-1.85 \times 10^3 \ J = - 41 g \times 0.903 \ J/g^0 C \times ( x - 25^0 c) }[/tex]

[tex]\mathbf{1.85 \times 10^3 \ J = 41 g \times 0.903 \ J/g^0 C \times ( x - 25^0 c) }[/tex]

[tex]\mathbf{(x - 25 ^0 C) = \dfrac{1.85 \times 10^3 \ J }{ 41 g \times 0.903 \ J/g^0 C}}[/tex]

[tex]\mathbf{(x - 25 ^0 C) = 49.97^0 C}}[/tex]

[tex]\mathbf{x = 49.97^0 C+25 ^0 C}}[/tex]

x = 74.97 °C

Learn more about specific heat here:

https://brainly.com/question/1430612

Answer:

C.  physical

Explanation:

A mixture is a physical combination. Mixtures are combinations of compounds and molecules without any chemical reaction taking place.

Mixtures have the following properties:

Answer:

diet soda has artificial sugar and regular soda has insane amounts of sugar

First, it combines with carbon dioxide in the soil to form a weak acid called carbonic acid. ... Carbonic acid slowly dissolves away minerals in rock, especially the carbonate minerals that make up limestone and marble. The weak acid decomposes the insoluble rock into watersoluble products that move into the groundwater.

Answer:

Ethanol has a higher octane number than gasoline, providing premium blending properties, according to the U.S.

Explanation:

Department of Energy. Minimum octane number requirements prevent engine knocking and maintain drivability.

Answer:

0.967mole

Explanation:

Given parameters:

Volume of NH₄Cl  = 21.67L

Unknown:

Number of moles  = ?

Solution:

If we assume that the volume was taken at standard temperature and pressure,

 Then;

  Number of moles  = [tex]\frac{volume }{22.4L}[/tex]  

 Number of moles  = [tex]\frac{21.67}{22.4}[/tex]   = 0.967mole

Answer:

C. Hydrogen Ions.

Explanation:

The pH level of soils is measured based upon the acidity or basicity level in the soil. The pH scale usually measures between 0-14. 7 is the neutral pH level of soil and a pH level below 7 is considered acidic and above 7 is alkaline.

So, soil with a high amount of hydrogen ions (H+) will be considered acidic. As the amount of hydrogen ions increases in the soil, the pH level of the soil decreases, making it acidic.

Therefore, option C is correct.

Answer:

H₂O₂

Explanation:

Hydrogen peroxide is a typical example of a compound molecule. A compound is made up of one or more atoms that are combined together in a definite grouping.

The properties of a compound is different from those of the elements that combines to from them.

Answer:

18.3%

Explanation:

Add the numbers together, and then take the number of grams of the substance, in this case copper, not coppper lol. divide the .45 by 2.45 to get 18.3

Answer:

False

Explanation:

I took the quiz and got it right

Answer:

Nitrogen and Oxygen make up 99% of the Earths atmosphere. Then Argon makes up the rest of the atmosphere.

Explanation:

moles=mass÷molar mass

n=m÷Mr

6.0=14.6÷Mr

Mr=14.6÷6.0

Molar mass= 2.433

Answer:

SiH4

Explanation:

4 hydrogens serve a the base and the Si is on top which forms a tetrahedral shape.

Answer:

B. 3+

Explanation:

When Fe²⁺ loses an electron, it becomes an Fe³⁺ ion.

   The loss of an electron in an atom makes the atom becomes positively charged. Further losing electrons makes the atom more positive.

 For the given ion;

 Fe²⁺   if it loses an electron more, it becomes Fe³⁺.

The expression is given as:

         Fe²⁺    →    Fe³⁺  +  e⁻

Answer:

VALENCE ELECTRONS are involved in the bonding of atoms

Explanation:

Hope that helps

Answer:

Di Sulphur tetraiodide is the chemical compound with the formula S2I4

Explanation:

Answer:

A. The number of atoms of each element is the same on the reactant side as the product side.

Explanation:

The equation demonstrates the law of conservation of mass in such a way that the number of atoms of each element is the same on the reactant side as the product side.

According to the law of conservation of mass "matter is neither created nor destroyed in a chemical reaction but they are changed from one form to another".

Moles of Carbon dioxide : n = 4.037 x 10⁻³

Given

2.43 x 10²¹ molecules of Carbon dioxide

Required

Moles

Solution

1 mol = 6.02 x `10²³ particles(molcules, atoms, ions)

Can be formulated :

N = n x No

n = moles

No = Avogadro's number 6.02 x `10²³

moles of Carbondioxide :

n = N/No

n = 2.43 x 10²¹ / 6.02 x `10²³

n = 4.037 x 10⁻³

Answer:

It kinda helps but not  really

Thanks for trying anyway doe!

Explanation:

Answer:

The answer is D

I searched it up to verify.

Answer: I think the possible answer is B or D

Explanation: There are few of the energies like: Gravitational, electrical, Chemical.....

Answer:

Antonie van Leeuwenhoek used single-lens microscopes, which he made, to make the first observations of bacteria and protozoa. His extensive research on the growth of small animals such as fleas, mussels, and eels helped disprove the theory of spontaneous generation of life.

Explanation:

Hope this helps and have a great day :)

Explanation: cirrocumulus

Answer:

The pair of arrows which represents the relationship of speeds of the two cars is;

The second option as shown in the attached drawing

Explanation:

The given parameters are;

The reading on the speedometer of one car = 20 m/s

The reading on the speedometer of the other car = 72 km/h = 20 m/s

The blue arrow = 20 m/s

Therefore, given that the speeds of both cars are equal (20 m/s = 72 km/h = 20 m/s),  the pair of arrows that represent the relationship of speeds of the two cars is two equal length blue arrows which is the second option

The attached diagram showing the pair of arrows that represents the relationship of speeds of the two cars is drawn using Microsoft Visio.