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3 years ago

Which method of testing substances is an sure way to identify a chemical reaction?

2 answers:

6 0

. There are four different clues that indicate a chemical reaction has taken place. They are a change in color or temperature, release of a gas, or production of a precipitate.

Pani-rosa [81]3 years ago

3 0

The answer is Color change observed, or changes in color of the material.

This is one of the most common observable chemical reaction we know, simplest example is the changing of color of litmus paper when in contact with acid.

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I WILL MARK BRAINLIEST!

xxMikexx [17]

Answer:

Explanation:

The answer is C

7 0

3 years ago

Which three forms of light are invisible light?

Flauer [41]

Radio waves
infrared
x-rays
and red and blue light are not a thing, their on a color spectrum called visible light.

3 0

3 years ago

Read 2 more answers

A particular person's eardrum is circular, with a diameter of 7.90 mm. How much sound energy (in J) is delivered to an eardrum i

antiseptic1488 [7]

Answer:

$4.90167\times 10^{-17}\ J$

Explanation:

I = Hearing intensity = $1\times 10^{-12}\ W/m^2$

A = Area = $\pi r^2$

d = Diameter = 7.9 mm

r = Radius = $\dfrac{d}{2}=\dfrac{7.9}{2}=3.95\ mm$

Power is given by

$P=IA\\\Rightarrow P=1\times 10^{-12}\times \pi \times (3.95\times 10^{-3})^2\\\Rightarrow P=4.90167\times 10^{-17}\ W$

t = Time the eardrum is exposed to sound = 1 second

Energy is given by

$E=Pt\\\Rightarrow E=4.90167\times 10^{-17}\times 1\\\Rightarrow E=4.90167\times 10^{-17}\ J$

The energy transferred to the eardrum is $4.90167\times 10^{-17}\ J$

3 0

3 years ago

Read 2 more answers

Semiconductors can simplistically be thought of as an intermediate state between insulators and conductors. In a semiconductor,

Triss [41]

Answer:

The semiconductor rod will conduct electricity

Explanation:

Glass rod does not conduct electricity. Glass is one of the best insulators of electricity. But when a glass rod is replace with a semi conductor, then the semi conductor rod starts conducting electricity as the electrons are free to move.

Semi conductors are special materials in which the energy band lies in between the conductor and the non conductor. The conductivity of a semi conductor increases with the increasing temperature.

In an semi conductor the electrons are free to move and as they starts moving they conduct electricity. Thus a semi conductor rod replacing a glass rod conducts electricity.

6 0

3 years ago

In attempting to pull a 1500 kg car out of a ditch, Al exerts a force of 200 N for 5 s, Bill exerts a force of 500 N for two s,

MArishka [77]

Answer:

Clyde will provide greater impulse

Explanation:

We have given that Al exerts a force of 200 N for 5 sec

We know that impulse is given by, impulse = force ×time = 200×5 =1000 N-s

Bill exerts a force of 500 N for 2 sec

So impulse = 500×2 = 1000 N-s

Now the force exerted by Clyde 300 N for 4 sec

So impulse = 300×4 = 1200 N-s

From above calculation we can see that Clyde provide greater impulse than any other

4 0

3 years ago