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Nezavi
1 month ago
15

Pure sodium metal placed in water will spark and ignite, as well as form bubbles and gas. What are the signs that this is a chem

ical reaction? Check all that apply.
Heat is produced.

Light is produced.

Heat is absorbed.

Bubbles appear.

A precipitate forms.

The color changes.
Physics
2 answers:
Softa [3K]1 month ago
7 0

Answer;

  • Heat is generated
  • Light is emitted
  • Bubbles form

Explanation;

  • Chemical reactions are characterized by the interaction of two or more substances, leading to the formation of a new substance, and are typically irreversible.
  • Indicators of chemical reactions include gas production, release of energy in the form of light or heat, formation of precipitates, and color changes.
kicyunya [3.2K]1 month ago
6 0

Answer:

Heat is generated

Light is emitted

Bubbles form

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An 800-N billboard worker stands on a 4.0-m scaffold weighing 500 N and supported by vertical ropes at each end. How far would t
Maru [3345]

Answer:

2.5 m

Explanation:

Billboard worker's weight = 800 N

Number of ropes = 2

Length of scaffold = 4 m

Weight of scaffold = 500 N

Tension present in rope = 550 N

The total torques will be

-800(4-x)-500\times 2+550\times 4=0\\\Rightarrow -800(4-x)=500\times 2-550\times 4\\\Rightarrow -800(4-x)=-1200\\\Rightarrow -x=\dfrac{1200}{800}-4\\\Rightarrow -x=-2.5\\\Rightarrow x=2.5\ m

The worker is positioned at 2.5 m

7 0
1 month ago
A tennis ball bounces on the floor three times. If each time it loses 22.0% of its energy due to heating, how high does it rise
Ostrovityanka [3204]

Answer:

H = 109.14 cm

Explanation:

Given,                                                            

Assume that the total energy equals 1 unit.                                

Energy remaining after the first collision = 0.78 x 1 unit

Balance after the first impact = 0.78 units

Remaining energy after the second impact = 0.78 ^2 units

Balance after the second impact = 0.6084 units

Remaining energy after the third impact = 0.78 ^3 units

Balance after the third impact = 0.475 units

The height reached after the third collision is equivalent to the remaining energy.

Let H denote the height achieved after three bounces.

0.475 (m g h) = m g H                  

H = 0.475 x h                                    

H = 0.475 x 2.3 m                          

H = 1.0914 m                      

H = 109.14 cm                      

6 0
1 month ago
A bathtub contains 65 gallons of water and the total weight of the tub and water is approximately 931.925 pounds. You pull the p
Keith_Richards [3271]

Response:

Q = 8,345 * v

Clarification:

We need an expression that shows how much water has been drained from the tub. This is represented by v, which indicates how many gallons have flowed out since the plug was taken out. Each gallon removed equates to 8.345 pounds of water, so the weight of the drained water Q in pounds as a function of v can be expressed as:

Q = 8,345 * v

Where v signifies the number of gallons emptied from the tub.

Have a great day! Let me know if there's anything else I can assist with.

8 0
1 month ago
The newly formed xenon nucleus is left in an excited state. Thus, when it decays to a state of lower energy a gamma ray is emitt
ValentinkaMS [3465]

Answer:3.87*10^-4

Explanation:

To determine the mass reduction, delta mass Xe, of the xenon nucleus due to its decay, we first use the provided wavelength of the gamma radiation to calculate its frequency via c = freq*wavelength.

From C=f*lambda we set up: 3*10^8=f*3.44*10^-12.

Solving gives frequency F=0.87*10^20 Hz.

Next, we calculate the emitted energy using the equation E=hf, which translates to E=f*Planck's constant.

Thus, E=0.87*10^20*6.62*10^-34, resulting in E=575.94*10^(-16).

This energy is then converted from joules to MeV.

Utilizing the formula E=mc^2, with c^2 = 931.5 MeV/u, enables us to find the reduction in mass, yielding

3.87*10^-4 u.

6 0
28 days ago
15. Three semicircles of radius 1 are constructed on diameter AB of a semicircle of radius 2. The centers of the small semicircl
inna [3103]

Answer:

The area that remains is 4.201 m²

Explanation:

Provided that

AB=D=  4 m  (R=2 m)

The area of the half-circle AB is

A=\pi R^2/2

A=2π

The area of the smaller half-circle is

a=5π/6 + 2√3/4  m²

a=5π/6 + √3/2  m²

<pThus, the remaining area = A - a

                                     = 2π - (5π/6 + √3/2) m²

The remaining area is expressed as  2π - (5π/6 + √3/2) m²

5 0
1 month ago
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