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Firlakuza [10]
3 years ago
5

Which is a sign of a chemical change? A) Ice cream left at room temperature melts. B) Calcium chloride is dissolved in H2O and d

isappears. C) Paint on a freshly painted wall dries and is no longer sticky. D) When H2S gas is bubbled into a lead acetate solution, a precipitate forms.
Physics
2 answers:
Eduardwww [97]3 years ago
7 0

D, because a physical change is when something changes but doesn't change into a new substance. A chemical change is when something changes into a new substance.

Katarina [22]3 years ago
5 0
Chemical change is any change that results in the formation of new chemical substances. (Thanks to google)

This the answer is D
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Answer:B

Explanation:Grote reber was the first scientist to map the milky way galaxy using radio waves.

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four children pull on the same stuffed toy at the same time , yet there is no net force on the toy.how is this possible?
Kay [80]
There was no net force on the stuffed toy, because the kids might have the same strength,  The same force is on both sides of it.  T<span>hey cancel each other out. They exert a force on the stuffed toy equal in strength but opposite in direction. The forces are balanced and the stuffed toy does not move.  </span>Its like a game of tug-o-war, but you and I have the same strength. the rope would be still and not moving. 
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3 years ago
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determine the maximum angle theta for which the light rays incident on the end of the optical fiber of radius 1 mm are subhect t
Vesna [10]

Answer:

Explanation:

Let the critical angle be C .

sinC = 1 / μ where μ is index of refraction .

sinC = 1 /1.2

= .833

C = 56°

Then angle of refraction r = 90 - 56 = 34 ( see the image in attached file )

sin i / sinr = 1.2 , i is angle of incidence

sini = 1.2 x sinr = 1.2 x sin 34 = .67

i = 42°.  

7 0
3 years ago
The peak value of an alternating current in a 1500-W device is 6.4 A. What is the rms voltage across it
horrorfan [7]

Answer:

6787.5 V

Explanation:

From the question,

P = IV..................... Equation 1

Where P = Power, I = rms current, V = rms voltage.

make V the subject of the equation

V = P/I................. Equation 2

Given: P = 1500 W, I = 6.4/√2 = 4.525 A

Substitute these values into equation 2

V = 1500(4.525)

V = 6787.5 V

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7 0
3 years ago
Two cars are traveling along perpendicular roads, car A at 40 mi/hr, car B at 60 mi/hr. At noon, when car A reaches the intersec
Serggg [28]

Answer:

\frac{dD}{dt} = -4 miles/hour

negative sign indicates that the distance is decreasing with time

Explanation:

Let at any time t after noon that is 12 p.m.  

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then distance between the two cars at time t

D^2= (40t)^2+(90-60t)^2............1

also, at time 1 p.m.

distance D^2= (40\times1)^2+(90-60\times1)^2

D=50 Km

differentiating equation 1 w.r.t. t we get

2D\frac{dD}{dt}= 2\times40t\times40+2(90-60t)(-60)

put t= 1 and D= 50 we get

2\times50\frac{dD}{dt}= 3200\times1-3600\times1

\frac{dD}{dt} = -4 miles/hour

3 0
3 years ago
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