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Triss [41]
4 years ago
9

Please help

Chemistry
1 answer:
suter [353]4 years ago
5 0

Answer:

1. Physical change

2. T

3. Chemical change

4. Physical

5. ?

6. ?

7. ?

Explanation:

There are no choices listed for 5, 6, and 7 but I can help with those if you add a picture or clarification.

You might be interested in
According to current theory, a major reason for bonding is
tatiyna
Covalent bond   a chemical bond formed by two electrons that are shared between two atoms
ionic bond<span>    a chemical bond formed by the electrostatic attraction between ions</span>
metallic bond<span>    a bond characteristic of metals in which mobile valence electrons are shared among positive nuclei in the metallic crystal</span>
6 0
3 years ago
Read 2 more answers
If a system performs 147 kJ of work while receiving 47 kJ of heat, what is change in its internal energy?
Verdich [7]

Answer:

-100 kJ

Explanation:

We can solve this problem by applying the first law of thermodynamics, which states that:

\Delta U = Q-W

where:

\Delta U is the change in internal energy of a system

Q is the heat absorbed/released by the system (it is positive if absorbed by the system, negative if released by the system)

W is the work done by the system (it is positive if done by the system, negative if done on the system)

For the system in this problem we have:

W = +147 kJ is the work done by the system

Q = +47 kJ is the heat absorbed by the system

So , its change in internal energy is:

\Delta U = +47 - (+147) =-100 kJ

6 0
3 years ago
The amount of radioactive carbon-14 in a sample is measured using a Geiger counter, which records each disintegration of an atom
sergij07 [2.7K]

Answer:

4121 years

Explanation:

From;

0.693/t1/2 = 2.303/t log No/N

t1/2= half life of the carbon-14

No= count rate of the living tissue

N= count rate of the sample

t = age of the sample

0.693/5730 =2.303/t log (13.5/8.2)

1.21 * 10^-4 = 2.303/t * 0.2165

1.21 * 10^-4 = 0.4986/t

t = 0.4986/1.21 * 10^-4

t = 4121 years

7 0
3 years ago
According to the website of the National Aeronautics and Space Administration (NASA), the average temperature of the universe is
charle [14.2K]

Answer : The temperature in degree Celsius is, -270.45^oC

Explanation :

The conversion used for the temperature from Kelvin to degree Celsius is:

^oC=K-273.15

where,

K = temperature in Kelvin

^oC = temperature in centigrade

As we are given the temperature in Kelvin is, 2.7

Now we have to determine the temperature in Kelvin.

^oC=K-273.15

^oC=2.7-273.15

^oC=-270.45

Therefore, the temperature in degree Celsius is, -270.45^oC

3 0
3 years ago
What is the percent by volume of ethanol (C2H60, or ethyl alcohol) in the final solution when 90 mL of ethanol is diluted to a v
r-ruslan [8.4K]

Answer:

16.0%.

Explanation:

Volume percent of a substance is the ratio of the substance volume to the solution volume multiplied by 100.

V % of ethanol = (volume of ethanol / volume of the solution) x 100.

volume of ethanol = 90.0 mL, volume of the solution = 550.0 mL.

∴ V % of ethanol = (90.0 mL / 550.0 mL) x 100 = 16.36% ≅ 16.0%.

8 0
3 years ago
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