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SpyIntel [72]
3 years ago
5

Henry mixed salt and water together in a cup until he observed a clear solution. He measured the mass of the solution. Then he p

laced the cup outside for several sunny days during the summer. After a week, he observed that only solid salt remained in the cup and the mass had decreased. Henry concluded that a physical and chemical change occurred in this investigation.
Which statements correctly defend or dispute his conclusion?

A- He is correct. Dissolving salt in water is a physical change, but evaporating the water is a chemical change. Formation of a solid is evidence that a chemical change occurred.
B- He is correct. Evaporation is a physical change, but dissolving salt in water is a chemical change. The change in mass is evidence that a chemical change occurred.
C- He is incorrect. Dissolving salt in water and evaporation of the water are both physical changes. The reappearance of salt is evidence that the change was reversible by a physical change, so it could not be a chemical change.
D- He is incorrect. Dissolving salt in water and evaporation of the water are both chemical changes. The reappearance of salt is evidence that the change was reversible by a chemical change, so it could not be a physical change.
Physics
2 answers:
Andrei [34K]3 years ago
7 0

Answer:

B) He is correct. Evaporation is a physical change, but dissolving salt in water is a chemical change. The change in mass is evidence that a chemical change occurred.

Explanation:

hope this helps!! :)

Tomtit [17]3 years ago
6 0

Answer:

B- He is correct. Evaporation is a physical change, but dissolving salt in water is a chemical change. The change in mass is evidence that a chemical change occurred.

Explanation: Dissolving Salt in water is a Chemical Change, Because the Salt arrangement is different in solid state than dissolved in water. As we can see in the image below, once the Salt is dissolved, it is separated into its ions, Na+ and Cl- Now, The evaporation process is a physical change, because the water doesn´t change its configuration H20 and it only changes its form, as we can see in the image below.

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A 10kg object experiences a horizontal force which causes it to accelerate 5 m/s2 moving it a distance of 20 m horizontally. How
mr_godi [17]

Answer:

The work done by the force is 1000 J.

Explanation:

Given:

Mass of object (m) = 10 kg

Acceleration of the object (a) = 5 m/s²

Displacement of the object (S) = 20 m

Using Newton's second law, we have:

Force = Mass × Acceleration

F=ma

Plug in the given values and solve for force 'F' acting on the object. This gives,

F=(10\ kg)(5\ m/s^2)\\\\F=50\ N

Now, work done by the force 'F' is equal to the product of force 'F' and the displacement it cause in its direction which is 20 m.

Therefore, the work done by the force is given as:

Work = Force × Displacement

W=FS

Plug in the values given and solve for 'W'. This gives,

W=50\ N\times 20\ m \\\\W=1000\ J

Therefore, the work done by the force is 1000 J.

7 0
4 years ago
Say that you are in a large room at temperature TC = 300 K. Someone gives you a pot of hot soup at a temperature of TH = 340 K.
Sliva [168]

To solve the problem it is necessary to take into account the concepts related to energy efficiency in the engines, the work done, the heat input in the systems, the exchange and loss of heat in the soupy the radius between the work done the lost heat ( efficiency).

By definition the efficiency of the heat engine is

\epsilon = 1- \frac{T_c}{T_h}

Where,

T_c = Temperature at the room

T_h  =Temperature of the soup

The work done is defined as,

dW = \epsilon(dQ_h)

Where Q_h represents the input heat and at the same time is defined as

dQ_h =c_v (dT_h)

Where,

c_V =Specific Heat

The change at the work would be defined then as

dW = \epsilon(dQ_h)

dW = \epsilon c_v (dT_h)

dW = (1-\frac{T_c}{T_h})c_v (dT_h)

W = \int dW = \int (1-\frac{T_c}{T_h})c_v (dT_h)

W = c_v (T_h-T_c)-c_v T_c ln(\frac{T_h}{T_c})

On the other hand we have that the heat lost by the soup is equal to

dQ_h =c_v (dT_h)

Q_h =c_v (T_h-T_c)

The ratio between both would be,

\frac{W}{Q_h} = \frac{c_v (T_h-T_c)-c_v T_c ln(\frac{T_h}{T_c})}{c_v (T_h-T_c)}

\frac{W}{Q_h} = \frac{1+ln(\frac{T_h}{T_c})}{1-\frac{T_h}{T_c}}

Replacing with our values we have,

\frac{W}{Q_h} = 1+\frac{ln(\frac{340K}{300K})}{1-\frac{340K}{300K}}

\frac{W}{Q_h} = 0.0613

Therefore the fraction of heat lost by the soup that can be turned into useable work by the engine is 0.0613.

5 0
3 years ago
8.92 A 45.0 kg woman stands up in a 60.0 kg canoe 5.00 m long. She walks from a point 1.00 m from one end to a point I .00 m fro
omeli [17]

The distance that the canoe moves in this process is 1.29 meters.

We first have to find the center of mass

X = \frac{MsXs+McXc}{Mw+Mc} \\\\

Where

Ms = Woman's mass = 45

Mc = Canoe's mass = 60kg

Xs = position from left= 1 cm

Xc = position from left end of canoe's mass = 2.5cm

When we put these values into the equation we have:

X=\frac{45*1+60*2.5}{45+60} \\\\= 1.857\\

The center of gravity lies at the center of this boat. Therefore,

Xc = \frac{L}{2} \\\\L = 5 m long\\\\\frac{5}{2} =2.5

5.00 - 1. 00 = 4 meters

\frac{45*4+60*2.5}{45+60} = 3.14meters\\\\

To get the distance that is moved by this canoe

distance = 3.143-1.857

= 1.286

≈ 1.29 meters

The distance that the canoe moves in this process is 1.29 meters.

Read more on brainly.com/question/13198009?referrer=searchResults

6 0
2 years ago
Read the passage.
Paladinen [302]
<h2>Answer: B)Scientists’ understanding of cells continually improved as the results of studies built upon each other over time and formed the cell theory.</h2>

Explanation:

Nowadays we know <u>cells are essential microscopic units that make up the living beings, capable of reproducing independently. </u>

However, this is the result of a long process of discoveries and studies made since the 19th century, in which the continuous improvement of new technologies was helpful.

In fact, it is wel known the English scientist Robert Hooke was the first to discover the existence of cells by looking through a compound microscope at a cork sheet, realizing that it was made up of small polygonal holes (like those of a honeycomb) that reminded him of the chambers in which the monks stayed (called cells). Then, during the next centuries more studies were made until we had the current knowledge about the structure of a cell.

7 0
3 years ago
How do the full valance shells of the elements in the far right column of the periodic table affects how they react and take par
7nadin3 [17]
The full valence shell means that they do not react in chemical bonding.
The main purposes of chemical bonding is to obtain a stable structure.

Since the valence shell is stable,there is no need for chemical bonding since the whole atom is stable.
4 0
2 years ago
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