What is science all about?

Answer:

Intravenous injection.

Explanation:

Injections are the needle used for the transfer of chemicals or drugs from outside environment directly in to the body of an individual. Different body regions are used to inject different drugs depending on their function and mode of action.

Intravenous injections are the needles used to inject the drug directly into the blood stream in the veins and in the muscles. This intravenous injection prevents the over dosage of drugs and proves quite effective in its function.

Thus, the answer is intravenous injection.

Answer:

Law of definite proportion

Explanation:

A compound is a substance which is composed of two or more elements. According to the law of definite proportion, a compound is made up of element in definite and fixed ratio (by mass) therefore elements in compounds comprises of fixed percent. This law was given by English chemist john Dalton in 1808.

Answer:

1: atomic number is 26

2: number of valence electrons is 2

3: number of orbits is 4

4: atomic mass is 56

5: number of neutrons is 30

6: number of electrons in n=3 is 14

Explanation:

one is air and the other is a liquid 

IE1 = 578 kJ/mol 

IE2 = 1820 kJ/mol 

IE3 = 2750 kJ/mol 

IE4 = 11600 kJ/mol

If the following set of successive ionization energies are your ionization values this would likely belong to Aluminum. Since there is a huge point between the third and fourth ionization energies, which designates that the atom reached noble gas configuration after the third electron was removed. The element which has 3 valence electrons in the third period is aluminum.

First let us calculate the initial molarity of the 2.45 L of solution. Molar mass = 171.34 g/mol

moles Ba(OH)2 = 74.28 g * (1 mole / 171.34 g) =  0.4335 moles

Molarity (M1) = 0.4335 moles / 2.45 L = 0.177 M

Now using the formula M1V1 = M2V2, we can calculate how much to dilute (V1):

0.177 * V1 = 0.1 * 1

V1 = 0.56 L

Therefore 0.56 L of the initial solution must be diluted to 1 L to make 0.1 M

Answer:

7.859 × 10^-1 g/mL

Explanation:

D=mass/volume

10.782g/13,72ml= 0.78586 g/ml

7.859 x 10^-1 g/ml

The density of one gold atom is approximately 19.34 g/cm³, calculated by dividing its mass by its volume.

To calculate the density of one gold atom, Need to find its volume and then divide its mass by that volume.

Step 1: Calculate the volume of the gold atom.

The volume of a sphere can be calculated using the formula:

[tex]V_{sphere} = (4/3)\pi r^3[/tex]

Given that the diameter (d) of the gold atom is 272 pm (picometers), you can find the radius (r) by dividing the diameter by 2:

r = 272 pm / 2 = 136 pm = 1.36 x [tex]10^{-8} cm[/tex] (since 1 pm = [tex]10^{-10[/tex] cm)

Now, plug this radius into the formula for the volume of the sphere:

[tex]V_{sphere[/tex] = (4/3)π(1.36 x [tex]10^{-8[/tex] cm)^3 ≈ 1.69 x [tex]10^{-23[/tex] cm^3

Step 2: Calculate the density of one gold atom.

Now that you have the volume of one gold atom, you can calculate its density using the given mass of 3.27 x [tex]10^{-13[/tex] ng (nanograms). First, convert the mass to grams:

1 ng = [tex]10^{-9[/tex] g, so 3.27 x [tex]10^{-13[/tex] ng = 3.27 x [tex]10^{-22[/tex] g

Now, use the formula for density, which is density (ρ) = mass (m) / volume (V):

ρ = (3.27 x [tex]10^{-22[/tex] g) / (1.69 x [tex]10^{-23[/tex] cm^3) ≈ 19.34 g/[tex]cm^3[/tex]

So, the density of one gold atom is approximately 19.34 g/[tex]cm^3[/tex].

Answer:

Sulfur ₁₆S³²

Explanation:

The sulfur have sixteen protons sixteen neutrons and sixteen electrons. The sum of neutrons and protons is equal to atomic mass. So the given element have sixteen protons and sixteen electron, the atomic mass would be 32 and the element with atomic mass 32 is sulfur.

The number of electrons are equal to the number of protons. In the given element two electrons are more than number of protons. It means element gain two extra electron from another element and it is present in ionic form.

It is present in given form:

S²⁻

Electronic configuration:

S₁₆ = [Ne] 3s² 3p⁴

To complete the octet sulfur gain two electrons from other element and get stable.

Answer:

[tex]^{32}_{16}S^{2-}[/tex]

Explanation:

Atomic number : It is defined as the number of electrons or number of protons present in a neutral atom.

However, when we talk about the atomic number of the ion, it is not equal to the number of electrons as electron can be gained or loosed.

This is why, more appropriately, the number of the protons which are present in the nucleus of the atom is called the atomic number.

Thus, number of protons = atomic number = 16

The element must be sulfur.

Since, number of protons is not equal to the number of electrons, thus the isotope will not be neutral.

There are 2 more electrons than the number of protons and thus, the isotope will be having a charge of -2.

Mass number is the number of the entities present in the nucleus which is the equal to the sum of the number of protons and electrons.

Mass number = Number of protons + Number of neutrons  = 16 + 16 = 32 neutrons

The identity is:- [tex]^{32}_{16}S^{2-}[/tex]

Final answer:

The mass of 15 cm³ of gold, with a density of 19.3 g/cm³, is 289.5 g when calculated using the formula m = d × V.

Explanation:

The density of gold is 19.3 g/cm³.

To find the mass of 15 cm³ of gold, you can use the formula for density, which is mass divided by volume (d = m/V).

Since we know both the density and the volume, we can rearrange the formula to solve for mass (m = d × V).

In this case, the mass (m) would be 19.3 g/cm³ times 15 cm³, which equals 289.5 g.

Answer: Option (D) is the correct answer.

Explanation:

A chemical change is defined as the change which occurs due to change in chemical composition of a substance. A chemical change always leads to the formation of a new compound or substance.

For example, when an electric current passes through liquid water, hydrogen gas passes accumulates at one electrode and oxygen accumulates at the other.

Since, atoms of water are separating out. As a result, chemical properties will change. This means that a chemical change has occurred.

Also, bonds of water, ([tex]H_{2}O[/tex]) are breaking down. Hence, energy will be absorbed to break the bonds.

Whereas energy is always released upon formation of bonds.

Thus, we can conclude that the statement a chemical change has occurred, with energy being absorbed, is true.

First we have to refer to the reaction between the acid and the base: 

H2SO4 + 2 NaHCO3 ---> 2 H2O + 2 CO2 + Na2SO4 

From this balanced equation we can see that for every 1 mol of acid (H2SO4), we need 2 mol of base (NaHCO3) to neutralize it. Given 28 ml of 5.8 M acid, we need to find out how many mols of acid that is: 

28mL * (1L/1000mL) * 5.8 mol/L =  0.1624 mol H2SO4

Since we need 2 mol of base per mol of acid, we need:

 2*0.1624 mol = 0.3248 mol NaHCO3 

MolarMass of NaHCO3 is 84.01 g/mol 

0.3248 mol*(84.01g/mol) = 27.29 g NaHCO3

Answer: The mass of sodium hydrogen carbonate that must be added is 27.28 g

Explanation:

To calculate the number of moles for given molarity, we use the equation:

[tex]\text{Molarity of the solution}=\frac{\text{Moles of solute}\times 1000}{\text{Volume of solution (in mL)}}[/tex]

Molarity of sulfuric acid solution = 5.8 M

Volume of solution = 28 mL

Putting values in above equation, we get:

[tex]5.8M=\frac{\text{Moles of sulfuric acid}\times 1000}{28mL}\\\\\text{Moles of sulfuric acid}=0.1624mol[/tex]

The chemical equation for the reaction of sulfuric acid and sodium hydrogen carbonate follows:

[tex]H_2SO_4(aq.)+2NaHCO_3(aq.)\rightarrow Na_2SO_4(aq.)+2CO_2(g)+H_2O(l)[/tex]

By Stoichiometry of the reaction:

1 mole of sulfuric acid reacts with 2 moles of sodium hydrogen carbonate.

So, 0.1624 moles of sulfuric acid will react with = [tex]\frac{2}{1}\times 0.1624=0.3248mol[/tex] of sodium hydrogen carbonate

To calculate the number of moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

Molar mass of sodium hydrogen carbonate = 84 g/mol

Moles of sodium hydrogen carbonate = 0.3248 moles

Putting values in above equation, we get:

[tex]0.3248mol=\frac{\text{Mass of sodium hydrogen carbonate}}{84g/mol}\\\\\text{Mass of sodium hydrogen carbonate}=(0.3248mol\times 84g/mol)=27.28g[/tex]

Hence, the mass of sodium hydrogen carbonate that must be added is 27.28 g

Final answer:

The solute that increases the boiling point the most in a 0.15 m aqueous solution is one that dissociates into the most particles, like NaCl, because it has a larger effect on boiling point elevation than a non-dissociating substance like glucose.

Explanation:

The solute that produces the highest boiling point in a 0.15 m aqueous solution is determined by the number of particles it provides in the solution upon dissolving. According to the colligative property known as boiling point elevation, the more particles a solute generates, the higher the increase in the boiling point. Salts such as NaCl dissociate into ions, thereby increasing the boiling point of the solution more than non-dissociating molecules like glucose. Therefore, a solute like NaCl, which dissociates into two separate ions Na+ and Cl- would generate a higher elevation than glucose at the same molality because the ionization of NaCl results in twice the number of particles in the solution.

Using the formula ΔT = Kb × m (where ΔT is the increase in boiling point, Kb is the molal boiling-point elevation constant, and m is the molality), we can calculate the boiling point elevation. With a given Kb for water of 0.51°C/m, a 0.15 m solution of NaCl would lead to a higher boiling point than a 0.15 m solution of a non-electrolyte like glucose. This is because each mole of NaCl provides 2 moles of particles, doubling the ΔT value compared to glucose which does not dissociate.

All isotopes of the same element have the same number of protons. Number of neutrons in different atoms of the same element is free to vary. Since, different elements react differently, different elements have different numbers of protons. Atoms with the same number of protons and vary neutrons behave chemically similar. The number of electrons in a neutral atom depends on the number of protons. All chemical reactions involve transfer or sharing of electrons it stands to reason, neutrons are NOT responsible for chemical reactivity. It's arguable whether protons or electrons dictate chemical reactivity certainly the SUBATOMIC nuclear particle that dictates reactivity is the PROTON.

Final answer:

Dicing potatoes is a physical change since it alters their shape and size but not their chemical identity. This kind of physical change, while being irreversible, does not transform the potatoes into a new substance.

Explanation:

Dicing potatoes is indeed a physical change. This is because when you dice potatoes, you are only changing their shape and size, not their chemical structure or identity. Physical changes can be reversible or irreversible, but they do not alter the fundamental identify of a substance.

Some examples of reversible physical changes include melting, where ice changes to liquid water and can be refrozen, and dissolving, such as when salt is dissolved in water and can be recovered by evaporating the water. Conversely, irreversible physical changes do not easily revert to the original form, such as cutting hair—once it is cut, it cannot grow back instantly.

In the case of dicing potatoes, the physical change is irreversible as you cannot restore the potatoes to their original, uncut state. However, the potatoes remain chemically identical before and after dicing.

The characteristic spectrum an element produces indicates the location of its electron as each unique spectral line indicates the electron's movement between specific energy levels or shells in the atom.

The location of an electron can be determined based on the spectrum that an element produces. When an electron absorbs energy, it moves to a higher energy level or shell, also known as an excited state. When it falls back to its original energy state, it emits energy in the form of electromagnetic radiation, producing a unique spectral line. This spectral line or pattern is characteristic of the element, and it can hint at an electron's location in a specific energy level or shell around the nucleus.

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The Net Ionic equation for the reaction between MgSO4 with Sr(NO3)2 is given by;  

Sr ⁺²(aq) + SO₄⁻²(aq) → SrSO₄(s)

That is:

MgSO₄(aq) + Sr(NO₃)₂(aq) → Mg(NO₃)₂(aq) + SrSO₄(s)

Therefore; the ionic equation required will be;

Sr ⁺²(aq) + SO₄⁻²(aq) → SrSO₄(s)

Level: High school

Subject: Chemistry

Topic: Chemical equation

Sub-topic: Net ionic equations

Answer: The correct answer is image 1 shows a monomer, and Image 2 shows a polymer.

Explanation:

A monomer is defined as the molecule that react with the same molecule to form a large molecule known as polymer. These are the repeating units in a polymer.

A polymer is a large molecule which are formed when a large number of  same type of molecules react together.

A macro-molecule is defined as a very large molecule such as proteins which are formed by the polymerization of monomers. They are known as natural polymers.

A synthetic polymer are defined as the polymers which are made by humans. They are known as artificial polymers.

In the images given, Image 1 represents a monomer known as ethylene and Image 2 is a polymer known as polyethylene.

Hence, the correct answer is image 1 shows a monomer, and Image 2 shows a polymer,

Answer:the answer is B

Explanation: did the test

Answer:

Explanation:

To determine if the bock will float you need:

The block has 3 dimmentions: lenght, wide and height, its volume is:

[tex]V=wide*lenght*height[/tex]

Once calculated it and measured the  weight, you calculate the density:

[tex]\rho=\frac{m}{V}[/tex]

If the density of the block is smaller than the density of water (arroung 1000 kg/m3) the block will float.

metric is the answer