All categories

3 years ago

Wich of these is not a sign of chemical change 1 A gas is given off

Physics

1 answer:

mash [69]3 years ago

5 0

<h3>Answer:</h3>

2. The material dissolves

<h3>Explanation:</h3>

The Question tests the understanding of chemical change and whether we know the signs that show its occurrence.

First we need to know what is chemical change;

Chemical change is a type of change that involves formation of a new substance different from the original substance.

Second we need to identify the signs that indicate the occurrence of a chemical change

Chemical change in chemical reactions is characterized by various signs which include;

Production of bubbles
Color change
Formation of a precipitate
Change of odor
Change in temperature.

Therefore, in this case, the material dissolving is not a sign that chemical change has taken place.

You might be interested in

PLEASE HELPPPP ME WITH THIS

lozanna [386]

I am not so sure about this it is too difficult

4 0

3 years ago

The cylinder with piston locked in place is immersed in a mixture of ice and water and allowed to come to thermal equilibrium wi

lukranit [14]

Answer:

a. volume of gas: (decreases)

b. temperature of gas: (same)

c. internal energy of gas: (same)

d. pressure of gas: (increases)

Explanation:

We have a gas (let's suppose that is ideal) in a piston with a fixed volume V.

Then we put in a reservoir at 0°C (the mixture of water and ice)

remember that the state equation for an ideal gas is:

P*V = n*R*T

and:

U = c*n*R*T

where:

P = pressure

V = volume

n = number of mols

R = constant

c = constant

T = temperature.

Now, we have equilibrium at T = 0°C, then we can assume that T is also a constant.

Then in the equation:

P*V = n*R*T

all the terms in the left side are constants.

P*V = constant

And knowing that:

U = c*n*R*T

then:

n*R*T = U/c

We can replace it in the other equation to get:

P*V = U/c = constant.

Now, the piston is (slowly) moving inwards, then:

a) Volume of the gas: as the piston moves inwards, the volume where the gas can be is smaller, then the volume of the gas decreases.

b) temperature of the gas: we know that the gas is a thermal equilibrium with the mixture (this happens because we are in a slow process) then the temperature of the gas does not change.

c) Internal energy of the gas:

we have:

P*V = n*R*T = constant

and:

P*V = U/c = constant.

Then:

U = c*Constant

This means that the internal energy does not change.

d) Pressure of the gas:

Here we can use the relation:

P*V = constant

then:

P = (constant)/V

Now, if V decreases, the denominator in that equation will be smaller. We know that if we decrease the value of the denominator, the value of the quotient increases.

And the quotient is equal to P.

Then if the volume decreases, we will see that the pressure increases.

4 0

2 years ago

Why does refracting light bend when it enters a denser or less dense medium?

Rzqust [24]

Answer: The light bends because light travels fast but it slows down in a denser medium. For example light refracts in water or it bends after passing through air. When light passes through air ( a less dense medium ) then through water ( a more dense medium ) the beam of light bends because light travels more slowly in a denser medium then it picks up its pace again once it passes. The density of the substance determines how much the light is refracted. I hope this makes sense and I hope this answered your question!! :)

4 0

3 years ago

What is the speed of a wave if it has a wavelength of<br> 42 m and a frequency of 7 hertz?

Nimfa-mama [501]

Answer:

♕ $\large{ \red{ \tt{Step - By - Step \: Explanation}}}$

☃ $\underline{ \underline{ \blue{ \large{ \tt{G \: I \: V \: E\: N}}}}} :$

Frequency ( f ) = 7 Hertz
Wavelength ( λ ) = 42m

♨ $\underline {\underline{ \orange{ \large{ \tt{T \: O \: \: F \: I \: N\: D}}}} }:$

Wave velocity ( v )

☄ $\underline{ \underline{ \large{ \pink{ \tt{S\: O \: L \: U \: T\: I \: O \: N}}}}}:$

✧ $\red{ \boxed{ \large{ \purple{ \sf{Wave \: velocity(v) = Frequency(f) \times Wavelength(λ)}}}}}$

~Plug the known values and then multiply!

↦ $\large{ \tt{7 \times 42}}$

↦ $\boxed{ \boxed{ \large{ \bold{ \tt{294 \: m {s}^ {- 1} }}}}}$

☥ $\large{ \boxed{ \boxed{ \large{ \tt{Our \: Final \: Answer : \underline{ \large{ \tt{294 \: m {s}^{ - 1}}}}}}}}}$

---------------------------------------------------------------

❁ $\underline{ \large{ \red{ \tt{D\: E\: T \: A \: I \: L\: E \: D \: \: I\: N \: F \: O}}}} :$

Frequency ( f ) : The number of complete waves , set up in a medium in one second is called frequency of the wave. The SI unit of frequency is Hertz ( Hz ). For example : if a sound wave completes 15 compressions and 15 rarefactions in one second , it's frequency is 15 Hz.

Wavelength ( λ ) : The distance between two consecutive troughs or crests in a transverse wave or the distance between two consecutive compressions or rarefactions in a longitudinal wave us called wavelength. It is the distance travelled by a wave in a time equal to it's time period. It's SI unit is metre ( m ).

Wave velocity ( v ) : The velocity with which a wave propagates in a medium is called wave velocity. It's SI unit is m/s.

# KILL : Excuses

KISS : Opportunities

MARRY : Goals

♪ Hope I helped! ♡

☂ Have a wonderful day / night ! ツ

✎ $\underbrace{ \overbrace{ \mathfrak{Carry \: On \: Learning}}}$ ✔

▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁

4 0

3 years ago

Can someone plz help me with this

Elena-2011 [213]

1st Law: Objects that are in motion tend to stay in motion. This motion can change with external forces.

<span>If you were to stop pedaling on bike while in motion, you will notice that you will keep moving. This is because a moving body (you) has inertia. If there wasn't any friction between the tires and the ground, between the axles and wheel, any air resistance, or any other force that acts against you, then you could be coasting indefinitely! </span>

<span>2nd Law: Force is equal to the mass times acceleration. </span>

<span>When you pedal, you are applying a force onto the pedal. This force is then translated through tension to apply torque onto the wheel. Turning the wheel will make you accelerate in the lateral direction. </span>

<span>3rd Law: For every action, there is an equal and opposite reaction. </span>

<span>Without this, you could pedal and pedal, but you will be not go anywhere! It is essentially the friction between the tires and the ground that propels you forward. If the ground did not apply to the tire the same amount of force that the tire was applying to the ground, the tire would not "catch" and no friction would be applied. And if there was no third law, the weight of you and your bike would "sink" into the ground because the ground would not be applying a normal force back onto you.

hope this helps and if you have any questions just hmu and ask :)</span>

3 0

2 years ago