Which evidence is an indication that a chemical reaction has occurred?


formation of a gas


melting of a substance


boiling of a substance


freezing of a substance

Answer:

Check explanation section.

Explanation:

In order to understand balanced force and unbalanced forces the first law of Newton should be considered as a basic knowledge.

For Balanced forces, there is equal equality in the direction of the forces. In balanced forces, there is no acceleration.

For unbalanced forces, there is acceleration that is go say there is going to be movement. Therefore, net force is equal to unbalanced forces.

(i) Suitcase dropped from a height.

Answer: since there is movement that is acceleration, then the force here is unbalanced force. The resultant force is downwards.towards the greater force direction.

(ii) A bicycle moving with constant velocity on a straight road.

Answer: As the bicycle moves at constant velocity on the straight road the force here is Balanced. Frictional forces balances the forces from the cyclist.

(iii) The rope does not move in a tug of war on applying force at both ends.

Answer: Balanced force.

Answer:

c) non polar Covalent

Explanation:

this is a molecule formed by atoms of the same element . they both have similar electronegativities and thus cancel out . This makes it a perfect Covalent molecule . The fact that it's a symmetrical molecule makes it non polar. a symmetrical molecule is a molecule formed by the overlap of orbitals of two atoms of the same element ( that is to say , there's no dipole )

Answer:

oxygen

Explanation:

plants use oxygen

Answer:

The answer is 94 miles an hour.

Explanation:

Speed equals distance divided by the time taken to cover that distance. So to find the average speed of the train just divide the distance covered (846 miles) by the time taken by the train to cover that distance (9 hours) and that equals 846/9 equals 94 miles in one hour.

Answer:

D

Explanation:

Because speed is a scalar quantity which he has only magnitude and no direction while velocity is a vector quantity because it has both magnitude and direction.

Answer: all of them

Explanation:

Answer:

The answers X i just took the test

Explanation:

1. Q = 112.8 kJ

2. Q = 5.01 kJ

The heat to change the phase can be formulated :

Q = mLf (melting/freezing)

Q = mLv (vaporization/condensation)

Lf=latent heat of fusion

Lv=latent heat of vaporization

1. m=50 g=0.05 kg

Lv for water = 2256 kJ/kg

[tex]\tt Q=m.L_v\\\\Q=0.05\times 2256\\\\Q=\boxed{\bold{112.8~kJ}}[/tex]

2. m=15 g=0.015 kg

Lf for water = 334 kj/kg

[tex]\tt Q=m.L_f\\\\Q=0.015\times 334\\\\Q=\boxed{\bold{5.01~kJ}}[/tex]

Answer:

2. reasoning

Explanation:

PLS GIVE BRAINLIEST

Answer:

A.

Explanation:

The car has kinetic energy.

Answer:

The polyatomic cation that will react with MnO₄⁻ to form a neutral compound is NH₄⁺ (ammonium ion) to form NH₄MnO₄ (Ammonium permanganate).

Answer:

7.62 plug into the equation for freezing

0= 592/7.62x x 90

0 = 77.69x x 90

x=0

therefore according to balton's law, it is required to have 0 + 27.222222222 (balton's number) to get the energy required.

answer is 27.222222 rounded 27. cheers.

Answer:

So it takes 80 calories of heat to melt 1 g of an ice cube, now do the math. (Hope this helped)

Explanation:

Answer:

It’s caused by a disturbance.

It carries energy.

Explanation:

A wave is a disturbance that transmits energy from one point to another. It does no necessarily carry the particles or matter of the medium.

Waves usually carries energy. It is this energy they use in creating disturbances.

Not all waves carries matter; a good example is electromagnetic waves. Also, electromagnetic waves do not require a medium for propagation.

Answer:

(m1+m2)v

Explanation:

where m1 is the mass of the first body

m2 is the mass of the second body

v is the velocity

Answer:

Na the valency electrons is 1

The ion charge is positive 1

K the valency electrons is 1

The ion charge is positive 1

Explanation:

Mg the valency electron is 2 The ion charge is positive 2

Ca the valency electron is 2 The ion charge is positive 2

Al the valency electron is 3 The ion charge is positive 3

O the valency electron is 2 The ion charge

is negative 2

F the valency electron is 1 The ion charge is negative 1

Cl the valency electron is 1 The ion charge

is negative 1

N the valency electron is 3 The ion charge is negative 3

S the valency electron is 2 The ion charge is

negative 2

Na the valency electrons is 1, The ion charge is positive 1 and K the valency electrons is 1, The ion charge is positive 1.

Mg the valency electron is 2 The ion charge is positive 2, Ca the valency electron is 2 The ion charge is positive 2 and Al the valency electron is 3 The ion charge is positive 3.

O the valency electron is 2 The ion charge, is negative 2 and F the valency electron is 1 The ion charge is negative 1, Cl the valency electron is 1 The ion charge is negative 1

N the valency electron is 3 The ion charge is negative 3, S the valency electron is 2 The ion charge is negative 2.

Therefore, Na the valency electrons is 1, The ion charge is positive 1 and K the valency electrons is 1, The ion charge is positive 1.

To learn more about valency, refer to the link:

https://brainly.com/question/12744547

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Answer:

270

Explanation:

Once you add more mass to something the mass doesn’t go away you add more mass.

hope this helps!

Answer:

Diversity?

Explanation:

Think thats bio

Answer:

0.025 moles of NO₂  will produced

Explanation:

Given data:

Moles of NO₂ formed = ?

Volume of HNO₃ = 25.0 mL

Molarity of HNO₃ = 2 M

Solution:

Chemical equation:

Cu + 4HNO₃   →        Cu(NO₃)₂ + 2NO₂ + 2H₂O

Number of moles of HNO₃:

Molarity = number of moles /  volume in L

2M = number of moles / 0.025 L

Number of moles = 2 M × 0.025 L

Number of moles = 0.05 mol

Now we will compare the moles of HNO₃  with NO₂  from balance chemical equation.

                                  HNO₃            :          NO₂

                                      4                :            2

                                 0.05               :         2/4×0.05 =0.025

0.025 moles of NO₂  will produced.

Wavelength  = 6.25 x 10⁻¹⁰ m

Energy=3.1805 x 10⁻¹⁶ J

Radiation energy is absorbed by photons

The energy in one photon can be formulated as

[tex]\large{\boxed{\bold{E\:=\:h\:.\:f}}}[/tex]

Where

h = Planck's constant (6,626.10⁻³⁴ Js)

f = Frequency of electromagnetic waves

f = c / λ

c = speed of light

= 3.10⁸

λ = wavelength

Frequency : 4.8 x 10¹⁷ /s

the wavelength  :

[tex]\tt \lambda=\dfrac{c}{f}\\\\\lambda=\dfrac{3.10^8}{4.8.10^{17}}=6.25\times 10^{-10}~m[/tex]

Energy :

[tex]\tt E=6.626.10^{-34}\times 4.8\times 10^{17}=3.1805\times 10^{-16}~J[/tex]

Sorry,for table 3 , I can't find it

Answer:rarrrrrrr

Explanation:

Answer:

Basically, the more hot the state is, the more kinetic energy it will have. This means that answer D. would be right, as it goes from coldest to hottest states!

Answer:

The answer is D. solid, liquid, gas, plasma

Explanation:

Answer:

Explanation:

In creating this list, one will have to start from the atom (which is the smallest in the list) to the giant polymer (which is the largest in the group). The arrangement below will also be based on there molecular weight.

oxygen molecule (this is the first because it is an atom)

water molecule (this is lighter in weight than carbon dioxide)

carbon dioxide

amino acid molecule (most amino acids have a lesser molecular weight than glucose)

glucose (has a molecular weight of 180.156 g/mol)

protein molecule (several proteins have a lesser molecular weight than starch)

starch molecule (has a molecular weight of 359.33 g/mol)

The arrangement of molecules in the ascending order is: oxygen, water, carbon dioxide, amino acid, glucose, starch, and protein.  

• The size of the molecules can be determined by knowing their molecular weights.  

• The sum of the atomic weights of the atoms in the molecule is known as the molecular weight of the molecule.  

• The molecular weight of water is 18 gram per mole, glucose 180.2 g/mol, starch 360 g/mol, carbon dioxide 44 g/mol, protein 20000 g/mol, amino acid for example glycine 75 g/mol, and oxygen 16 g/mol.  

Thus, the molecules can be arranged with the smallest to the largest as oxygen, water, carbon dioxide, amino acid, glucose, starch, and protein.

To know more about:

https://brainly.com/question/19922822

Answer:

all of the above

Explanation:

a hypothesis is indeed the second step. it also can be tested since you made it beforehand. it also is supposed to be educated. so all of the above.

Answer:

All of the above

Explanation:

d. Ba₃(PO₄)₂(s)+6HNO₃(aq)

Double-Replacement reactions. Happens if there is an ion exchange between two ion compounds in the reactant to form two new ion compounds in the product  

To predict whether this reaction can occur or not is one of them, the precipitation reaction. A precipitation reaction occurs if two ionic compounds which are dissolved reacted to produce one of the products of the ion compound does not dissolve. Formation of these precipitating compounds that cause reactions can occur  

Because A precipitate is formed, then compounds of CO₃²⁻ and PO₄³⁻ except for Compounds of Li +, Na +, K +, Rb +, Cs +, and NH₄ + are generally included in the insoluble compound

So the reaction :

3Ba(NO₃)₂(aq)+2H₃PO₄(aq)⇒Ba₃(PO₄)₂(s)+6HNO₃(aq)

A precipitate is formed ⇒ Ba₃(PO₄)₂

Answer:

Explanation:

The new pressure can be found by using the formula for Boyle's law which is

[tex]P_1V_1 = P_2V_2[/tex]

Since we are finding the new pressure

[tex]P_2 = \frac{P_1V_1}{V_2} \\[/tex]

From the question we have

[tex]P_2 = \frac{11.2 \times 0.86}{15} = \frac{9.632}{15} \\ = 0.64213333...[/tex]

We have the final answer as

Hope this helps you

Given:

Initial Volume [tex] \sf (V_1) [/tex] = 11.2 L

Initial Pressure [tex] \sf (P_1) [/tex] = 0.860 atm

Final Volume [tex] \sf (V_2) [/tex] = 15.0 L

To Find:

Final Pressure [tex] \sf (P_2) [/tex]

Concept/Theory:

[tex] \bf{ \underline{Boyle's \: Law} \: (Pressure - Volume \: Relationship)}[/tex]

"At constant temperature, the pressure of a fixed amount of gas varies inversely with the volume of the gas."

[tex] \bf{P \propto \dfrac{1}{V} \: (at \: constant \: T \: and \: n)}[/tex]

It can be also stated as "At constant temperature, the product of pressure and volume of fixed amount of a gas remains constant."

[tex] \bf{PV = Constant}[/tex]

If the initial pressure and volume of a fixed amount of gas at constant temperature are [tex] \sf (P_1) [/tex] & [tex] \sf (V_1) [/tex] and final pressure of the gas is [tex] \sf (P_2) [/tex] and volume occupied is [tex] \sf (V_2) [/tex], then according to Boyle's law;

[tex] \bf{P_1V_1 = P_2V_2 = Constant}[/tex]

OR

[tex] \bf{\dfrac{P_1}{P_2} = \dfrac{V_2}{V_1}}[/tex]

Answer:

By using Boyle's Law, we get:

[tex] \rm \longrightarrow \dfrac{0.860}{P_2} = \dfrac{15.0}{11.2} \\ \\ \rm \longrightarrow P_2 = \dfrac{11.2}{15.0} \times 0.860 \\ \\ \rm \longrightarrow P_2 = \dfrac{9.632}{15.0} \\ \\ \rm \longrightarrow P_2 = 0.642 \: atm[/tex]

[tex] \therefore [/tex] Final Pressure [tex] \sf (P_2) [/tex] = 0.642 atm

Answer:

Evaporation from the hydrosphere provides the medium for cloud and rain formation in the atmosphere. The atmosphere brings back rainwater to the hydrosphere. The atmosphere provides the geosphere with heat and energy needed for rock breakdown and erosion. The geosphere, in turn, reflects the sun's energy back into the atmosphere.

Explanation:

Answer:  A wavelenghth is the distance between successive crests of one wave.