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2 years ago

Which statement correctly describes a physical change?

Chemistry

1 answer:

MArishka [77]2 years ago

4 0

Answer: Option (b) is the correct answer.

Explanation:

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

For example, melting of ice is a physical change as there occurs change in phase from solid state to liquid state of water. Whereas the structure of water remains the same.

Therefore, we can conclude that the statement which describes a physical change is that it may involve a change in phase but does not involve a change in the molecular structure.

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3 years ago

Answer A B C and D please for my chemistry hw

r-ruslan [8.4K]

Answer: The equations are provided below.

Explanation:

Skeleton equations are defined as the equations which simply indicate the molecules that are involved in a chemical reaction. These equations are unbalanced equations.

Balanced equations are defined as the chemical equation in which number of individual atoms on the reactant side must be equal to the number of individual atoms on the product side.

For A:

Water decomposes in the direct current to form hydrogen and oxygen.

Skeleton Equation: $H_2O(l)\rightarrow H_2(g)+O_2(g)$

Balanced Equation: $2H_2O(l)\rightarrow 2H_2(g)+O_2(g)$

For B:

Mercury (II) oxide decomposes in heat to form mercury, oxygen.

Skeleton Equation: $HgO(s)\rightarrow Hg+O_2$

Balanced Equation: $2HgO(s)\rightarrow 2Hg+O_2$

For C:

Calcium carbonate when heated forms calcium oxide and carbon dioxide.

Skeleton Equation: $CaCO_3(s)\rightarrow CaO(s)+CO_2(g)$

Balanced Equation: $CaCO_3(s)\rightarrow CaO(s)+CO_2(g)$

For D:

Group 2 hydroxides, when heated forms oxide and water vapor.

Skeleton Equation: $Ca(OH)_2\rightarrow CaO+H_2O$

Balanced Equation: $Ca(OH)_2\rightarrow CaO+H_2O$

3 0

3 years ago

Which chemical weathering process is caused by oxygen and water acting on iron?

mash [69]

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2 years ago

Rank these acids according to their expected pKa values.ClCH2COOHClCH2CH2COOHCH3CH2COOHCl2CHCOOHIn order of highest pka to lowes

Ilia_Sergeevich [38]

Answer:

CH₃CH₂CH₂COOH > CH₃CH₂COOH > ClCH₂CH₂COOH > ClCH₂COOH

Explanation:

Electron-withdrawing groups (EWGs) increase acidity by inductive removal of electrons from the carboxyl group.

Electron-donating groups (EDGs) decrease acidity by inductive donation of electrons to the carboxyl group.

The closer the substituent is to the carboxyl group, the greater is its effect.
The more substituents, the greater the effect.
The effect tails off rapidly and is almost zero after about three C-C bonds.

CH₃CH₂-CH₂COOH — EDG — weakest — pKₐ = 4.82

CH₃-CH₂COOH — reference — pKₐ = 4.75

ClCH₂-CH₂COOH — EWG on β-carbon— stronger — pKₐ = 4.00

ClCH₂COOH — EWG on α-carbon — strongest — pKₐ = 2.87

6 0

2 years ago

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