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andrezito [222]
3 years ago
7

A student dips a strip of metal into a liquid. Which is evidence that only a physical change has occurred? The metal bends more

easily. The metal changes color. The metal gives off light. The metal gives off heat.
Chemistry
2 answers:
Kazeer [188]3 years ago
7 0

Answer: Option (a) is the correct answer.

Explanation:

A change which brings no chemical change in composition of the substance is known as a physical change.

For example, bending of metal strip is a physical change as it does not change the chemical composition of substance.  

Whereas metal changes color, metal gives off light, and metal gives off heat are all chemical changes.

Thus, we can conclude that out of the given options, the metal bends more easily is evidence that only a physical change has occurred.

bixtya [17]3 years ago
4 0
The metal bends more easily is the correct answer all the others are cause via chemical reactions
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What is the percent composition by mass of hydrogen in nh4hco3
Simora [160]

<u>Answer:</u> The percent composition by mass of hydrogen in given compound is 6.33 %

<u>Explanation:</u>

We are given:

A chemical compound having chemical formula of NH_4HCO_3

It is made up by the combination of 1 nitrogen atom, 5 hydrogen atoms, 1 carbon atom and 3 oxygen atoms

To calculate the percentage composition by mass of hydrogen in the compound, we use the equation:

\%\text{ composition of Hydrogen}=\frac{\text{Mass of hydrogen}}{\text{Mass of compound}}\times 100

Mass of compound = [(1\times 14)+(5\times 1)+(1\times 12)+(3\times 16)]=79g/mol

Mass of hydrogen = (5\times 1)=5g/mol

Putting values in above equation, we get:

\%\text{ composition of Hydrogen}=\frac{5g/mol}{79g/mol}\times 100=6.33\%

Hence, the percent composition by mass of hydrogen in given compound is 6.33 %

6 0
3 years ago
Why dilute H2SO4 is added to oxali acid solution in redox reaction​
Sphinxa [80]

To prevent the hydrolysis and to catalyse the reaction.

Explanation:

  • Sulphuric acid is the catalyst and also a dehydrating agent in this reaction.
  • Sulphuric acid is using in redox reaction because sulphuric acid is providing H+ ions which is necessary for this reaction to occur more quickly, but the sulphate ions from the sulphuric acid barely react during this process. So H2SO4 is adding in this reaction to make it more acidic.
  • H2SO4 is preventing hydrolysis by providing excess H+ ions into the reaction. H2SO4 is stable towards the direction of oxidation.
7 0
3 years ago
Which of the following processes have a ΔS &lt; 0? Which of the following processes have a ΔS &lt; 0? carbon dioxide(g) → carbon
Umnica [9.8K]

Answer:

All of the above processes have a ΔS < 0.

Explanation:

ΔS represents change in entropy of a system. Entropy refers to the degree of disorderliness of a system.

The question requests us to identify the process that has a negative change of entropy.

carbon dioxide(g) → carbon dioxide(s)

There is  a change in state from gas to solid. Solid particles are more ordered than gas particles so this is a negative change in entropy.

water freezes

There is  a change in state from liquid to solid. Solid particles are more ordered than liquid particles so this is a negative change in entropy.

propanol (g, at 555 K) → propanol (g, at 400 K)

Temperature is directly proportional to entropy, this means higher temperature leads t higher entropy.

This reaction highlights a drop in temperature which means a negative change in entropy.

methyl alcohol condenses

Condensation is the change in state from gas to liquid. Liquid particles are more ordered than gas particles so this is a negative change in entropy.

6 0
3 years ago
I have attached all the problems, but really if you just do one so I understand how to do it, that would be great!
Ivahew [28]

Answer:

Answer of question a is 345J.

Explanation:

In question a following is given in data:

-mass of iron (m) = 10.0 g

-temperature (ΔT) = final temperature- initial temperature= 100-25=  75 degree Celsius

-Specific Heat capacity of iron (c)= 0.46J/g°C.

Heat (Q)=?

Solution:

Formula for Heat is :

Q=m x c x ΔT

Q= 10 x 0.46 x 75

Q= 345 J.  

so, 345 joules of heat is needed to increase the temperature of 10 grams of iron.

  • From the above formula all other questions can easily be solved from the same procedure.
4 0
3 years ago
1.) Activation energy is _____.
balandron [24]
To answer the questions,

(1) Activation energy is the amount of energy that is needed for the reaction to proceed, converting the reactant to products. The answer is letter B.

(2) The rate of chemical reaction normally increases as the reactant concentration is increased. The answer is letter C. 

6 0
3 years ago
Read 2 more answers
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