For many years, experiments showed that light had wave-like properties. For this reason, scientists described light

as a wave. More recently, experiments produced data that could not be explained by the wave theory of light. The

idea of particle properties was introduced

Why did the theory of light change over time?

O The theory was too old and needed to be updated

New scientists did not agree with the older theory

O The scientific question changed, so the theory had to change.

O Repeated experimentation introduced new discoveries.

Answer:

See explanation

Explanation:

Hypatia is popular for her work in mathematics. She also did some work in the area of astronomy. Her well know work in mathematics is her ideas about conic sections.

She was born the Theon of Alexandria and she was a professional mathematician in her life time.

She was the greatest mathematician of her time and she was telling leader of the Neoplatonist school of philosophy in Alexandria. By so doing, she conquered the culture of sexism in her time.

She was trained by her father in mathematics and eventually replaced him. She was the last major mathematician in the Alexandrian tradition.

Answer: Matter can be broken down into two categories: pure substances and mixtures. Pure substances are further broken down into elements and compounds. Mixtures are physically combined structures that can be separated into their original components. A chemical substance is composed of one type of atom or molecule :)!

Answer:

WCl₂, WCl₄, WCl₅, WCl₆

Explanation:

Molar Mass of Tungsten = 184 g/mol

Mass of Chlorine = 35.5 g/mol

In the first compound;

Percentage of tungsten = 72.17 %

Upon solving;

72.17 % = 184

100 % = Total mass

Total mass of compound = 254.95g

Mass of chlorine = 254.95 - 184 = 70.95 (Dividing by 35.35; This is approximately 2 Chlorine atoms.

The Formular is WCl₂

In the second compound;

Percentage of tungsten = 56.45 %

Upon solving;

56.45 % = 184

100 % = Total mass

Total mass of compound = 325.95 g

Mass of chlorine = 325.95 - 184 = 141.95g (Dividing by 35.35; This is approximately 4 Chlorine atoms.

The Formular is WCl₄

In the third compound;

Percentage of tungsten = 50.91 %

Upon solving;

50.91 % = 184

100 % = Total mass

Total mass of compound = 361.42 g

Mass of chlorine =  361.42 - 184 = 177.42 (Dividing by 35.35; This is approximately 5 Chlorine atoms.

The Formular is WCl₅

In the fourth compound;

Percentage of tungsten = 46.39 %

Upon solving;

46.39 % = 184

100 % = Total mass

Total mass of compound = 396.64 g

Mass of chlorine = 396.64 - 184 = 212.64 (Dividing by 35.35; This is approximately 6 Chlorine atoms.

The Formular is WCl₆

Answer:

pH = 9.26

Explanation:

Let's make the reaction of this weak base:

C₅H₅N  +  H₂O  ⇄    C₅H₅NH⁺  +  OH⁻     Kb

We do not know the Kb, but we can discover it from pKb

Kb = 10^⁻pKb  →  10⁻⁸'⁷⁷ = 1.70×10⁻⁹

So, let's make the expression for Kb

Kb = [OH⁻] . [C₅H₅NH⁺] / [C₅H₅N]

In the equilibrum, we would have  0.20 moles from the begining - x (react)

So we would proudce x moles of OH⁻ and x moles of C₅H₅NH⁺.

In conclussion:

1.70×10⁻⁹ = x . x / (0.20 - x)

To avoid the quadratic formula we can miss the x from the substraction

1.70×10⁻⁹ = x² / 0.20

1.70×10⁻⁹ . 0.20 = x²

We avoid the x from the (0.20-x), because the base is so concentrated, and Kb is very small.

x = √(1.70×10⁻⁹ . 0.20) → 1.84×10⁻⁵

That's the value of [OH⁻], so we can calculate pOH

- log [OH⁻] = pOH → - log 1.84×10⁻⁵ = 4.73

Then pH = 14 - pOH

14 - 4.73 = 9.26

The pH of a 0.20 M aqueous solution of pyridine is approximately 9.26.

Given,

pKb = 8.77

Concentration = 0.20M

The pKb is related to the pKa by the equation: pKa + pKb = 14.

pKa = 14 - 8.77 = 5.23.

Since pyridine is a base, it can be treated as the conjugate base of its corresponding acid. The acid is the pyridinium cation, which is formed by the protonation of pyridine.

Now, the equilibrium between the pyridine (base) and the pyridinium ion (acid):

C₅H₅N + H₂O ⇌ C₅H₅NH⁺ + OH⁻

The equilibrium constant expression for this reaction can be expressed as:

Kb = [tex]\frac{([C_5H_5NH^+][OH^-])}{[C_5H_5N]}[/tex]

At equilibrium, the concentration of OH⁻ will be equal to the concentration of [C₅H₅NH⁺], as pyridine is a weak base and will not significantly dissociate in water.

Kb = [tex]\frac{[OH^-]^2}{[C_5H_5N]}[/tex]

Kb = [tex]10^{(-8.77)[/tex]

Kb = [tex]\frac{[OH^-]^2}{[C_5H_5N]}[/tex]

[tex]10^{(-8.77)[/tex] = [tex]\frac{[OH^-]^2}{(0.20 M)}[/tex]

[OH⁻]² = [tex]10^{(-8.77)[/tex] ₓ 0.20 M

[OH⁻] = [tex]\sqrt{10^{-8.77} \times 0.20M}[/tex]

[OH⁻] ≈ 1.42 x 10⁻⁵ M.

The pOH (the negative logarithm of the hydroxide ion concentration):

pOH = [tex]-log_{10}([OH^-])[/tex]

pOH = [tex]-log_{10}[/tex](1.42 x 10⁻⁵)

pOH ≈ 4.85

Since pH + pOH = 14, the pH:

pH = 14 - pOH

pH = 14 - 4.85

pH ≈ 9.26

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Answer: A) The angle of the Sun's rays!

Answer:

A) The angle of the Sun's rays!

Explanation:

Answer:

A family is a vertical column .

The elements in a family have similar chemical properties.

Answer:evaporation

Explanation:

Answer:

Pretty sure its evaporation, if its not I'm very sorry.

Answer:

i

[tex]J_{m} = 20 [/tex]

ii

[tex]J_{m} = 22.5 [/tex]

Explanation:

From the question we are told that

  The first temperatures is [tex]T_1 =  25^oC =  25 +273 =298 \ K[/tex]

   The second temperature is  [tex]T_2 =  100^oC =  100 +273 = 373 \ K[/tex]

Generally the equation for  the most highly populated rotational energy level is mathematically represented as

     [tex]J_{m} = [ \frac{RT}{2B}]  ^{\frac{1}{2} } - \frac{1}{2}[/tex]

Here R is the gas constant with value [tex]R =8.314 \ J\cdot K^{-1} \cdot mol^{-1}[/tex]

Also  

      B is given as [tex]B=\ 0.244 \ cm^{-1}[/tex]

   Generally the energy require per mole to move 1 cm is  12 J /mole

So   [tex]0.244 \ cm^{-1}[/tex]  will require x J/mole

           [tex]x =  0.244 *  12[/tex]

=>          [tex]x =  2.928 \ J/mol [/tex]

So at the first temperature

     [tex]J_{m} = [ \frac{8.314 * 298  }{2*  2.928 }]  ^{\frac{1}{2} } - 0.5 [/tex]

=>  [tex]J_{m} = 20 [/tex]

So at the second temperature

           [tex]J_{m} = [ \frac{8.314 * 373  }{2*  2.928 }]  ^{\frac{1}{2} } - 0.5 [/tex]

=>  [tex]J_{m} = 22.5 [/tex]

Answer:

Atomic radii vary in a predictable way across the periodic table. As can be seen in the figures below, the atomic radius increases from top to bottom in a group, and decreases from left to right across a period. Thus, helium is the smallest element, and francium is the largest.

Explanation:

Answer:

Climate

Explanation:

Answer:

as much as i can see i think it goes like this?:

1.H202--> H20+02

Answer is 2,2,1 bc

1.when you add 2 to H202 its 2H202 so H is 4 and O is 4,

2.when you add 2 to H20 its 2H20 so H is 4 and O is 2 (so H is done and good on both sides we have 4 H)

3. and then when you add 1 to O2 its still O2 you dont need to add anything bz when you add the 2O from 2H2O with O2 its 4 O so everything's good (i explained it a bit messy so you can message me if you got questions)

2. Ag20->Ag+ O2

answer is 2,4,1

1.when you add 2 to Ag2O2 it becomes 2Ag2O (so Ag is 4 and O is 2)

2. you add 4 to Ag bc on the left side when you added 2 Ag became 4 so now its equal on both sides (they're both 4)

3.you add 1 (basically dont add anything bc you dont write 1 just leave it as O2) bc on left side you got O2 and the same on right side (if you got questions message me:))

Answer: the % is 99.73 and the mass is 40.986

Explanation:

Answer:

acidic because of electrical issues and the body of electrical equipment

Answer:

112.92 s.

Explanation:

Let M₁ be the molar mass of N₂O

Let t₁ be the time taken for N₂O to effuse.

Let M₂ be the molar mass of I₂

Let t₂ be the time taken for I₂ to effuse.

Molar mass (M₁) of N₂O = (14×2) + 16 = 28 + 16 = 44 g/mol

Time (t₁) of effusion of N₂O = 47 s

Molar mass (M₂) of I₂ = 127 × 2 = 254 g/mol

Time (t₂ ) of effusion of I₂ =?

The time take for the same amount of I₂ to effuse can be obtained as follow:

t₂/t₁ = √(M₂/M₁)

t₂/47 = √(254 / 44)

Cross multiply

t₂ = 47 × √(254 / 44)

t₂ = 112.92 s

Therefore, it will take 112.92 s for the same amount of I₂ to effuse.

Answer:

QC= [O2]^3/[F2]^10

Explanation:

Answer:

Explanation:

energy of solar radiation = 70 W / m²

energy absorbed in 1 hour by an area of .18 m²

= 70 x .5 x .18 x 60 x 60 J

= 22.68 x 10³ J

bond energy of i mole bond = 348 x 10³ J

bond energy of 6.02 x 10²³ bonds = 348 x 10³  J

bond energy of one bond = 57.8 x 10⁻²⁰ J  

No of bonds broken by energy 22.68 x 10³

= 22.68 x 10³  / 57.8 x 10⁻²⁰

= .3923 x 10²³

= 39.23 x 10²⁰ .

Answer:

Explanation:

We shall use the formula S₁V₁ = S₂V₂

S₁ = .1180 M , V₁ = 25.98 mL

S₂ = ? , V₂ = 52.50 mL

.1180 M  x 25.98 = 52.50 x S₂

S₂ = .0584 M

Molarity of the acid solution = .0584 M .

The concentration of the acid solution is 0.058 M.

The equation of the reaction is;

CH3COOH(aq) + KOH(aq) ----->  CH3COOK(aq) + H2O(l)

The following are known;

Concentration of base CB = 0.1180 M

Volume of base VB =  25.98 mL

Concentration of acid CA = ?

Volume of acid VA = 52.50 mL

Number of moles of acid NA = 1

Number of moles of base NB = 1

Using;

CAVA/CBVB =NA/NB

CAVANB = CBVBNA

CA=  CBVBNA/VANB

CA = 0.1180 M × 25.98 mL × 1/52.50 mL × 1

CA = 0.058 M

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Answer:

a) - 0.2 M

b) - 0.2 M

c)- 0

Explanation:

The chemical formula of copper (II) bromide is CuBr₂. Its molar mass (MM) is calculated as follows:

MM(CuBr₂)= MM(Cu) + (2 x MM(Br) = 63.5 g/mol + (2 x 80 g/mol)= 223.5 g/mol

a). Molarity = moles CuBr₂/1 L solution

moles CuBr₂ = mass/MM = 18.7 g x 1 mol/223.5 g = 0.084 mol

Volume in L = 375 mL x 1 L/1000 mL = 0.375 L

M = 0.084 mol/(0.375 L) = 0.223 M ≅ 0.2 M

b). When is added to water, CuBr₂ dissociates into ions as follows:

CuBr₂ ⇒ Cu²⁺ + 2 Br⁻

We have 1 mol Cu²⁺ (copper (II) cation) per mol of CuBr₂. Thus, the concentration of copper (II) cation is:

0.2 mol CuBr₂ x 1 mol Cu²⁺/mol CuBr₂ = 0.2 M

c). The concentration of acetate anion is 0. There is no acetate anion in the solution (the anion from CuBr₂ is bromide Br⁻).

Answer:

states that rock layers with the same unique groupings of fossils are of the same geologic age.

Explanation:

The principle of fossil correlation states that the presence of similar fossils of dead organisms in rock layers indicates that the organisms under investigation must have existed around the same geologic time. This principle can be used in dating the periods when the organism being studied lived.

The geological age system follows a chronological format in tracking the age of an item under study by grouping the time periods that organisms lived into strata.

Answer:

9.) Homeostasis

10.) Epidermis

11.) Cytoplasim

12.) Classification

Answer: The size actually does not matter. But planets with smaller mass will have less gravity decreasing their weight. Other for larger mass planets, more mass is more gravity which is also more weight.

Explanation:

Answer:

The solubility of Zn(OH)₂ at 25ºC is 1.96x 10⁻⁶,

Explanation:

The solubility is the maximum amount of a solute that can be dissolved in a certain volume of liquid (usually water) at a given temperature.

First, we write the dissolution reaction of Zn(OH)₂ in water, which is:

Zn(OH)₂ (s)  ⇄ Zn²⁺ + 2 OH⁻

We know that the Kps, that is, the dissolution equilibrium constant for this compound at 25ºC is 3.0x 10⁻¹⁷.

Therefore, the Kps is:

Kps= [Zn²⁺][OH⁻]² (since Zn(OH)₂ is solid, it is not accounted for).

Given the reaction, we can see that for every single Zn²⁺ ion, two OH⁻ ions are produced. Therefore, if the concentration of Zn²⁺ dissolved is x M, the concentration of OH⁻ dissolved will be 2x M.

Substituting these values in Kps, we have:

[Zn²⁺][OH⁻]² = (x)(2x)² = 3.0x 10⁻¹⁷

                            4x³ = 3.0x 10⁻¹⁷

                             x= ∛ (3.0x 10⁻¹⁷ ÷ 4)

                            x= 1.96x 10⁻⁶

Therefore, the molar solubility of Zn(OH)₂ at 25ºC will be 1.96x 10⁻⁶.

Answer:

Overall charge = -3

Explanation:

The atom of every chemical element is its smallest indivisible part. However, this atom further consists of subatomic particles namely: proton, electron, and neutron. The proton and electron are the positively charged and negatively charged particle respectively.

In a neutral atom, the amount of proton and electrons in that atom equates. However, the amount of electron and proton present in an atom determines the charge of that atom. For example, in this question, an atom is said to contain 17 protons, 17 neutrons and 20 electrons.

Since the negatively charged electrons (20) are more than the positively charged protons (17) by 3, hence, the net charge is -3.

Answer:

a right is 90 degrees

Answer:

the bike will go down 5 N

Answer:

C

Explanation: