What I need help fast!

Answer:

A change in the shape of a substance

Explanation:

Because when ths shape of a sunstance changes , its physical appearance changes .A physical change is a change to the physical—as opposed to chemical—properties of a substance. They are usually reversible. The physical properties of a substance include such characteristics as shape (volume and size), color, texture, flexibility, density, and mass.

Answer:

A.) It cannot be quickly replaced.

Explanation:

Aluminum is extremely useful to humans but is semi-difficult to produce. Because of this, your answer will be numero uno. (Or A.)

Answer:

Explanation:

by stoichiometry

nNH3/2=nH2/3

0.25/2=nH2/3

nH2=0.25×3/2

nH2=0.375 mol

so its 0.38 mol

Answer:

I have this quiz rn I will try 0.38 if it is right I’ll edit this and say that

Explanation:

Answer:

fewer collisions occur between particles or lowering the temperature

Explanation:

Answer:

A. Hot water increases the collision rate of the molecules, causing the

reaction to occur faster.

Explanation:

Hot water molecules move faster than cold water molecules.

Answer:

Explanation:

before the reaction you have K=2 and Cl=4

after the reaction K=2 and Cl=2 so it does not follow the law of conservation

Answer:

6 hours

Explanation:

If it is traveling at 50mph and needs to reah 300 miles, to figure this problem out you would want to divide 300 by 50 to get 6 hours. So it will take six hours until the car travels 300 miles

Hope this helps.

Answer: A car travels at a rate of 50 miles per hour. how long will it take the car to travel 300 miles?

Explanation: .

Applying the distance formula:

d = rt

where

d is distance (300 miles)

r is rate (50 mph)

t is time (hours)

.

300 = 30t

300/30 = t

10 hours = t

Answer:

b

Explanation:

i looked it up on Google

Answer:

B - What we change

Explanation:

Dependent Variable - What we measure

Control Variable - what stays the same

Conclusion - what we conclude

Hope this can Help!

:D

Answer:

V₂ = 112.14 mL

Explanation:

Given data:

Initial volume = 500 mL

Initial pressure = 270 mmHg (270/760 =0.355 atm)

Initial temperature = 55 °C (55 +273 = 328 K)

Final temperature = 100°C (100+273 = 373 K)

Final volume = ?

Final pressure = 1.8 atm

Formula:  

P₁V₁/T₁ = P₂V₂/T₂  

P₁ = Initial pressure

V₁ = Initial volume

T₁ = Initial temperature

P₂ = Final pressure

V₂ = Final volume

T₂ = Final temperature

Solution:

V₂ = P₁V₁ T₂/ T₁ P₂  

V₂ = 0.355 atm × 500mL × 373 K / 328 K × 1.8 atm

V₂ = 66207.5 atm .mL. K /  590.4 K.atm

V₂ = 112.14 mL

Answer:

0.92moles

Explanation:

Given reaction:

              2Fe + 3Cl₂ →  2FeCl₃

Mass of FeCl₃  = 100g

Unknown:

Number of moles of Cl₂  needed = ?

Solution:

To solve this problem, we work from the known specie to the unknown.

From the mass of the FeCl₃ given, we can solve for the number of moles of the unknown.

  Number of moles  = [tex]\frac{mass}{molar mass}[/tex]  

  Molar mass of  FeCl₃ = 56 + 3(35.5) = 162.5g/mol

   Number of moles  = [tex]\frac{100}{162.5}[/tex]  = 0.62mole

From the reaction expression;

           2 mole of FeCl₃ is produced from 3 moles of  Cl₂  

           0.62 mole of FeCl₃ will be produced from [tex]\frac{0.62 x 3}{2}[/tex]   = 0.92mole

The number of moles of Cl₂  = 0.92moles

Answer:

2HClO4 + Ca(OH)2 = Ca(ClO4)2 + 2H2O

Explanation:

Formula for aqueous perchloric acid is; HClO_4 (aq)

Formula for aqueous calcium hydroxide is; Ca(OH)_2 (aq)

Thus chemical equation is;

HClO4 + Ca(OH)2 = Ca(ClO4)2 + H2O

We have to balance it and so we now have;

2HClO4 + Ca(OH)2 = Ca(ClO4)2 + 2H2O

The chemical equation is said to be balanced if the number of atoms in the reactants and products is the same

Equation balanced ⇒ total number of atoms in reactants(on the left)= total number of atoms in products(on the right)

H₂+O₂---> H₂O

Reactants : H₂, O₂

Products : H₂O

not balanced

H₂O₂ ---> H₂O+O₂

Reactants : H₂O₂

Products : H₂O, O₂

not balanced

Na+O₂ ---> Na₂O

Reactants : Na, O₂

Products :  Na₂O

not balanced

N₂+H₂ ---> NH₃

Reactants : N₂, H₂

Products :  NH₃

not balanced

P₄+O₂---> P₄O₁₀

Reactants : P₄, O₂

Products :  P₄O₁₀

not balanced

Fe+H₂O ----> Fe₃O₄ + H₂

Reactants : Fe, H₂O

Products :  Fe₃O₄

not balanced

Ionic compounds are formed from metal and non-metal elements

The chemical formula of compounds (especially ionic compounds) can be determined from the charge of each ion.

Determination of the ionic charge of the constituent elements of the compound can be seen from the electron configuration to achieve stability according to the octet rule

The charge of each ion will be crossed in the compound

Aluminum bromide

Al³⁺ + Br⁻ ⇒ AlBr₃

Magnesium bromide

Mg²⁺ + Br⁻ ⇒ MgBr₂

Sodium sulfide

Na⁺ + S²⁻ ⇒ Na₂S

Sodium nitride

Na⁺ + N³⁻ ⇒ Na₃N

Answer:

T₂ = 573.86 K

Explanation:

Given data:

Initial volume = 1.32 L

Initial temperature = 30.0°C (30+273 = 303 K)

Final volume = 2.50 L

Final temperature in car = ?

Solution:

Solution:

The given problem will be solve through the Charles Law.

According to this law, The volume of given amount of a gas is directly proportional to its temperature at constant number of moles and pressure.

Mathematical expression:

V₁/T₁ = V₂/T₂

V₁ = Initial volume

T₁ = Initial temperature

V₂ = Final volume  

T₂ = Final temperature

Now we will put the values in formula.

V₁/T₁ = V₂/T₂

T₂ = V₂T₁/V₁

T₂ = 2.50 L × 303 K / 1.32 L

T₂ = 757.5 L.K / 1.32 L

T₂ = 573.86 K

Answer:

Greater

Greater

Explanation:

The amplitude of a wave is the height of the wave or the vertical displacement of the wave motion. We determine a wave amplitude usually by looking at the graph of the wave.

Amplitude is directly proportional to the energy of a wave. The higher the amplitude of a wave, the more its energy.

Frequency is the number of waves that passes a point at a particular instance of time. It is also directly proportional to the energy carried by a wave. The higher the frequency of a wave, the greater its energy.

Answer:

1 g

Explanation:

The following data were obtained from the question:

Original amount (N₀) = 32 g

Time (t) = 71.5 days

Half-life of phosphorus (t½) = 14.3 days

Amount remaining (N) =?

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

Half-life of phosphorus (t½) = 14.3 days

Decay constant (K) =?

K = 0.693 / t½

K = 0.693 / 14.3

K = 0.0485 /day

Finally, we shall determine the amount remaining as illustrated below:

Original amount (N₀) = 32 g

Time (t) = 71.5 days

Decay constant (K) = 0.0485 /day

Amount remaining (N) =?

Log (N₀/N) = Kt/2.303

Log (32/N) = 0.0485 × 71.5 / 2.303

Log (32/N) = 3.46775 / 2.303

Log (32/N) = 1.5058

Take the antilog of 1.5058

32/N = antilog (1.5058)

32/N = 32.05

Cross multiply

32 = N × 32.05

Divide both side by 32.05

N = 32 / 32.05

N = 0.998 ≈ 1 g

Thus, the amount remaining after 71.5 days is approximately 1 g.

The half-life of a radioactive substance refers to the time taken for the substance to Decay to half of its initial size. Hence, the mass of the substance left after 71.5 days is 1 gram.

After 14.3 days ;

After 14.3 × 2 = 28.6 days :

After 14.3 × 3 days = 42.9 days :

After 14.3 × 4 days = 57.2 days :

After 14.3 × 5 days = 71.5 days :

Hence, the mass of the sample left after 71.5 days would be 1 gram.

Learn more : https://brainly.com/question/18766174

Answer:

C. CH₄ is less than NH₃ because the NH bond is more polar than the CH bond

Explanation:

The intermolecular forces between ammonia is far stronger than for methane. Between the molecules of ammonia we have the presence of hydrogen bonds. This bond is absent in methane.

Hydrogen bonds are one of the strongest intermolecular forces. It is as a result of the electrostatic attraction between the hydrogen atom of one molecule and the electronegative atom N, O and F of another molecule.

The strength of the hydrogen bond depends on the electronegativity of the combining atoms.

Answer:

The reaction produces insoluble lead (II) sulphate which coats the surface of lead (II) nitrate  [Pb(NO3)]

Answer:

Explanation:

Firstly, it should be noted that melting and freezing points are the same. Thus, when a substance melts at a certain temperature, it means it can also start freezing/solidifying at that same temperature. That been said, when the substance P is a solid at a certain temperature, the other compound Q will boil at that same temperature and hence will be a gas at that same temperature.

If P is solid, it simply means that Q must still be in the liquid state.

From the question, we can see that, the melting point of P and the boiling point of Q are the same. The melting point of a substance is the temperature at which the solid turns to liquid while the boiling point of a substance is the temperature at which a liquid turns to a gas.

If P is solid, it simply means that Q must still be in the liquid state. It has not yet started boiling since the melting point of P and the boiling point of Q are the same.

Learn more: https://brainly.com/question/8553652

Answer:

Increase

Explanation:

Assuming a sinusoidal wave moving at a fixed wave speed, wavelength is inversely proportional to frequency of the wave: waves with higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths.

Answer:

carbon-12

Explanation:

carbon 6/12 isotope has 6 neutrones and it is considered as a metal.

Answer:

Ca3(PO4)2 and Na

Explanation:

The reaction equation is;

3Ca + 2Na3PO3 -------> Ca3(PO3)2 + 6Na

We must remember that calcium is above sodium in the electrochemical series. This implies that calcium can displace sodium from its solution. Calcium has a reduction potential of -2.87 V while sodium has a reduction potential of -2.71 V. The ion with the more negative reduction potential can easily displace the other in aqueous solution.

This explains why the reaction above is possible.

Answer:

1.181 × 10²⁴ molecules CO₂

General Formulas and Concepts:

Chemistry - Atomic Structure

Explanation:

Step 1: Define

86.34 g CO₂

Step 2: Identify Conversion

Avogadro's Number

Molar Mass of C - 12.01 g/mol

Molar Mass of O - 16.00 g/mol

Molar Mass of CO₂ - 12.01 + 2(16.00) = 44.01 g/mol

Step 3: Convert

[tex]86.34 \ g \ CO_2(\frac{1 \ mol \ CO_2}{44.01 \ g \ CO_2} )(\frac{6.022 \cdot 10^{23} \ molecules \ CO_2}{1 \ mol \ CO_2} )[/tex] = 1.18141 × 10²⁴ molecules CO₂

Step 4: Check

We are given 4 sig figs. Follow sig fig rules and round.

1.18141 × 10²⁴ molecules CO₂ ≈ 1.181 × 10²⁴ molecules CO₂

Answer: Due to the sharing of electrons, they exhibit characteristic physical properties that ... Here, we discuss two classes of compounds based on the bond type that ... Covalent bonds are characterized by the sharing of electrons between two or ... Describe the types of orbital overlap that occur in single, double, and triple bonds

Explanation: That's what I think it is.

Answer:

Sound.

Explanation:

Sound requires a medium such as air to travel.

1. ₉¹⁹F

2. Mg(OH)₂

3. 2H₂ + O₂ ⇒ 2H₂O

1. Fluorine, atomic number : 9 , mass number = 19

Symbol : ₉¹⁹F

protons=electrons=atomic number = 9

neutrons = mass number - atomic mass

[tex]\tt n=19-9=10[/tex]

Configuration : [He] 2s² 2p⁵

2. Magnesium hydroxide is an ionic compound and is a strong base consisting of 2 ions:

Positive ion: Magnesium: Mg²⁺

negative ion: Hydroxide: OH⁻

The charges of the two are crossed, so that the compound becomes:

Mg(OH)₂

3. Reaction :

H₂ + O₂ --------> H₂O

give coefficient :

aH₂ + bO₂ --------> H₂O

H, left = 2a, right 2⇒2a=2⇒a=1

O, left = 2b, right 1⇒2b=1⇒b=0.5

Reaction becomes :

H₂ + 0.5O₂ --------> H₂O x 2

2H₂ + O₂ --------> 2H₂O