If a chemical change has taken place, which of these is most likely true? A. Original substance can be easily recovered.
B. Composition of a substance is the same.
C. A completely new substance is formed.
D. An easily reversible process has taken place.

Answers

Answer 1
Answer: C. A completely new substance is formed.
Answer 2
Answer: C completely new substance

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Consider the reaction below. 2Al2O3 4Al + 3O2 How many moles of oxygen are produced when 26.5 mol of aluminum oxide are decomposed? 17.7 mol19.9 mol39.8 mol53.0 mol

Answers

2 Al2O3 = 4 Al + 3 O2

2 moles Al2O3 ------------ 3 moles O2
26.5 moles ----------------- moles O2

moles O2 = 26.5 * 3 / 2

moles O2 = 79.5 / 2 => 39.8 moles O2

Answer : C . ) 39.8 Is The Correct Answer

Write a balanced chemical equation based on the following description:solid chromium reacts with solid iodine to form solid chromium(III) iodide.​

Answers

The balanced chemical equation between solid chromium and solid iodine to form solid chromium(III) iodide is: 2 Cr(s) + 3 I₂(s) ⇒ 2 CrI₃(s)

Let's consider the unbalanced equation that occurs when ​solid chromium reacts with solid iodine to form solid chromium(III) iodide.​ This is a synthesis or combination reaction.

Cr(s) + I₂(s) ⇒ CrI₃(s)

We will balance it using the trial and error method.

First, we will balance I atoms by multiplying I₂ by 3 and CrI₃ by 2.

Cr(s) + 3 I₂(s) ⇒ 2 CrI₃(s)

Finally, we get the balanced equation by multiplying Cr by 2.

2 Cr(s) + 3 I₂(s) ⇒ 2 CrI₃(s)

The balanced chemical equation between solid chromium and solid iodine to form solid chromium(III) iodide is: 2 Cr(s) + 3 I₂(s) ⇒ 2 CrI₃(s)

You can learn more about balancing equations here: brainly.com/question/7181548

Answer:

2 Cr(s) + 3 I2(s) → 2 CrI3(s)

Explanation:

Reactants:

Solid Chromium

• Chromium is a transition metal with an elemental symbol → Cr

• It can exist as a stable monatomic solid → Cr(s)

Solid Iodine

• Iodine is a non-metal halide of Group 7A → I

• It exists as a diatomic solid → I2(s)

Products:

Chromium(III) iodide

• Chromium, Cr → roman numeral III → +3 charge → Cr3+

• Iodide, I → from group 7A → -1 charge → I-

• When ions combine, their charges or oxidation numbers crisscross to become subscripts

• Cr will have a subscript of 1 from I- → Cr

• I will have a subscript of 3 from Cr3+ → I3

• Subscript 1 is no longer indicated → CrI3(s)

Unbalanced Chemical Reaction: Cr(s) + I2(s) → CrI3(s)

Balancing the chemical reaction:

1. Balance I:

Cr(s) + I2(s) → CrI3(s)

• There are 2 I in the reactant and 3 I in the product side

• Balance I by adding the coefficient 3 in I2 and 2 in CrI2

• There would be a total of 6 I in the reactant and product sides

Cr(s) + 3 I2(s) → 2 CrI3(s)

2. Balance Cr:

Cr(s) + 3 I2(s) → 2 CrI3(s)

• There is 1 Cr in the reactant and 2 Cr in the product side

• Balance Cr by adding the coefficient 2 in Cr(s)

• There would be a total of 2 Cr in the reactant and product sides

2 Cr(s) + 3 I2(s) → 2 CrI3(s)

Standard reduction potentials are based on which element?A.
helium
B.
hydrogen
C.
lithium
D.
oxygen
E.
zinc

Answers

Answer: option B. Hydrogen

Explanation:

What is an occurrence of failure of Expansion Joints in Railways and Tracks. How common is it? What problems does it cause? What can be done to solve the problem?

Answers

Explanation:

The failure of expansion joints in railways and tracks is a relatively common problem. It can occur due to a number of factors, including:

* **Corrosion:** Expansion joints are made of metal, which is susceptible to corrosion. Corrosion can weaken the joints and make them more likely to fail.

* **Wear and tear:** Expansion joints are subject to a lot of wear and tear, especially in areas with heavy traffic. This can eventually lead to the joints failing.

* **Improper installation:** Expansion joints can fail if they are not installed properly. This can happen if the joints are not aligned correctly or if they are not properly secured.

When expansion joints fail, it can cause a number of problems, including:

* **Track misalignment:** A failed expansion joint can cause the track to become misaligned. This can lead to problems with train derailments.

* **Increased vibration:** A failed expansion joint can cause the track to vibrate more than it should. This can lead to increased wear and tear on the track and trains.

* **Reduced service life:** A failed expansion joint can reduce the service life of the track and trains. This can lead to increased costs for maintenance and repairs.

There are a number of things that can be done to solve the problem of expansion joint failure, including:

* **Regular inspection:** Expansion joints should be inspected regularly for signs of wear and tear. Any problems should be repaired immediately.

* **Use of high-quality materials:** Expansion joints should be made of high-quality materials that are resistant to corrosion and wear and tear.

* **Proper installation:** Expansion joints should be installed properly by qualified professionals.

In addition to these measures, there are a number of new technologies that are being developed to improve the performance of expansion joints. For example, some new joints are designed to be self-lubricating, which can help to reduce wear and tear.

By taking these steps, it is possible to reduce the occurrence of expansion joint failure and the problems that it can cause.

Answer: The failure of expansion joints in railways and tracks can occur due to various reasons such as wear and tear, aging, extreme weather conditions, or improper maintenance. While it is not possible to provide an exact frequency of occurrence, it is a common issue faced in railway infrastructure.

Rail expansion occurs when the temperature rises in summer, and the joints with proper length will be extruded and bulged due to rail expansion. If it is not serious, it will produce a bump, which will cause the train to run unsmoothly and send out an abnormal sound.

A traditional way of overcoming railway track expansion is to leave gaps between sections of rails. That solves the track thermal expansion for the railroad tracks joined end to end by rail joints (joint bars or fishplate).

Explanation:

The failure of expansion joints in railways and tracks is a relatively common problem. There are several factors that can contribute to the failure of these joints, including corrosion, wear and tear, and improper installation. Corrosion can weaken the joints, making them more likely to fail. Heavy traffic and regular use can also lead to wear and tear, which can eventually cause the joints to fail. Improper installation, such as misalignment or insufficient securing, can also result in joint failure.

When expansion joints fail, they can cause several problems. One of the main problems is track misalignment, which can lead to train derailments. A failed expansion joint can also increase vibrations in the track, leading to additional wear and tear on both the track and trains. Furthermore, the failure of expansion joints can reduce the service life of the track and trains, resulting in increased costs for maintenance and repairs.

To solve the problem of expansion joint failure, several measures can be taken. Regular inspections should be conducted to identify any signs of wear and tear, and any issues should be repaired promptly. Using high-quality materials for the construction of the joints can also help to improve their resistance to corrosion and wear and tear. It is important that the joints are installed properly by qualified professionals to ensure their effectiveness and longevity.

Additionally, new technologies are being developed to enhance the performance of expansion joints. For example, self-lubricating joints are being designed to decrease wear and tear. By implementing these measures and utilizing new technologies, the occurrence of expansion joint failure and the associated problems can be reduced.

It is crucial to address expansion joint failure promptly and take preventive measures to ensure the safety and efficiency of railway tracks and trains.

Which of these would be directly related to the science of ecology?
A: uncovering the genetic makeup of the eastern cottontail rabbit
B: developing strains of corn that can withstand a combination of drought and high winds
C: learning about foods that benefit the heart and blood vessels
D: studying how the mayfly population affects the number of trout in a stream

HELP!!!!!

Answers

D: studying how the mayfly population affects the number of trout in a stream

What is Ecology?

Ecology is the study of organisms and how they interact with the environment around them.

How mayfly is related to Ecology?

Mayflies provide direct and indirect services to humans and other parts of both freshwater and terrestrial ecosystems.

About 20% of mayfly species worldwide might have a threatened conservation status due to influences from pollution, invasive alien species, habitat loss and degradation, and climate change.

Thus, option D. is correct.

Learn more:

brainly.com/question/8395177

The answer is:

D.) studying how the mayfly population affects the number of trout in a stream

If its correct, I'm happy to help XD

Which of the following processes are physical changes?a) drying wet clothes
b) lighting a match from a matchbook
c) cutting snowflakes out of paper
d) melting butter for popcorn

Answers

C) cutting a snowflake out paper
because someone has to physically cut the paper into a snowflake
C) and d) are physical changes while b) is chemical