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Zigmanuir [339]
3 years ago
7

A firework exploding would be an example of a(n) ________. Physical change Endothermic reaction Exothermic reaction Formation of

a precipitate
Chemistry
1 answer:
omeli [17]3 years ago
6 0
I had this question on a test the answer is an exothermic reaction.
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1. When the temperature of a rigid hollow sphere containing 685 L of helium gas is
mote1985 [20]
<h3>Answer:</h3>

250.756 moles He

<h3>Explanation:</h3>

From the question we are given;

Volume, L = 685 L

Temperature, T = 621 K

Pressure, P = 189 × 10 kPa

We are required to calculate the number of moles of the gas,

Using the Ideal gas equation,

PV = nRT, where P is the pressure, V is the volume, T is the temperature, n is the number of moles, and R is the ideal gas constant.

We can replace the known variables and constant in the equation to get the unknown variable, n.

Using ideal gas constant as 8.3145 L.kPa/K/mol

n=\frac{PV}{RT}

n=\frac{(1890)(685)}{(8.3145)(621)}

n = 250.7557 moles

   n = 250.756 moles

The moles of helium contained in the sphere is 250.756 moles

6 0
3 years ago
In a covalent bond, the electrons are _____
Ivenika [448]

Explanation:

In a covalent bond the electrons are simultaneously attracted by the two atomic nuclei.

6 0
3 years ago
Read 2 more answers
Which of the following statements about decomposition reactions is true?
Andreyy89
C

Decomposition is of this form: A becomes B+C ... so after the reaction, the element A DECOMPOSES into two smaller elements, B and C.

Synthesis is the opposite: B+C becomes A AFTER THE REACTION.

Hope that helps :))
8 0
3 years ago
Read 2 more answers
What methods were used to clean up the Chernobyl and three mile island accidents?
Assoli18 [71]

<u>Answer</u>:

Electric evaporator has been used to clean up the Chernobyl and 3 mile island accident.

<u>Explanation</u>:

About 14 years back, there was a puff of radioactive steam from the evaporator used in the "Three-mile island" nuclear plant. It took two years for the electric evaporator to clean up the 2.2 million gallons of water that have been destroyed because of the nuclear power plant accident.

The steam that came out of the electric evaporator carried a radioactive form of hydrogen and tritium with itself. Cost of clean up was $1 billion.

6 0
4 years ago
Can someone help me with the questions in the images. if they are correct i will mark as brainliest
olga nikolaevna [1]

(1)

The health of coral colonies

The levels of carbon dioxide in the atmosphere

This is because corals are very sensitive to changes in the ocean's properties pH being included. Warmer oceans dissolves more carbon dioxide from the atmosphere hence making the waters slightly acidic. This will affect coral resulting in bleaching. This negatively affects the marine ecosystems since corals are usually at the bottom of the energy pyramid in these ecosystems.

(2)

Chlorofluorocarbons are very harmful to the environment when released into the atmosphere. They damage the ozone layer and therefore allow more UV rays from sunlight to reach the earth’s surface. They also have a  greenhouse effect causing the earth’s atmosphere to warm up. This ultimately leads to global warming and climate change.

(3)

It would allow storm systems to stall in an area

Jets streams are very significant in that they influence weather patterns across the world. They are responsible for the movement of pressure systems and global air cells and their accompanying weather patterns. Because they generally sit in between cold and warm air systems they are significant in moving these air masses around. When they are weak they cause an air system to linger including storms causing excessive flooding in an area.

(4)

Absorb and re-emit infrared radiation.

Produced by human activity

Greenhouse gases do not allow infrared radiation from the earth's surface to escape back to space. Infrared is the electromagnetic wave spectrum responsible for transferring heat energy. Therefore, when left to linger in the atmosphere, they cause the greenhouse effect. This is the reason for global warming.

(5)

Air temperature –, ice

Ocean temperature – ice, a chemical isotope of <em>foraminifera</em>

Carbon dioxide levels – a chemical isotope of <em>foraminifera</em>

Kind of plants – fossilized pollen grains

Rainfall- the rings

6 0
4 years ago
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