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3 years ago

Which statement correctly describes a physical change?

Chemistry

1 answer:

MArishka [77]3 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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Consider the nuclear equation below. 239/94 Pu—-> X+ 4/2 He. What is X?

Anna007 [38]

Answer:

X = U (Uranium)

Explanation:

Pu-->235/92 U + 4/2 He

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2 years ago

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Describe cold blooded animal.also some five example.

Vlad [161]

Answer:

Cold-blood animals are the animals that are not capable of regulating their body temperature,Cold blood animals included reptiles,fishes,amphibians,insects and other invertebrates.

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2 years ago

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Ag2S + Al(s) = Al2S3 + Ag(s) (unbalanced)

Dovator [93]

Answer:

1. 0.97 V

2. $Al_(_s_)/Al^+^3~_(_a_q_)~//~Ag^+~_(_a_q_)/Ag_(_s_)$

Explanation:

In this case, we can start with the half-reactions:

$Ag^+~_(_a_q_)->~Ag_(_s_)$

$Al_(_s_)~->~Al^+^3~_(_a_q_)$

With this in mind we can add the electrons:

$Ag^+~_(_a_q_)+~e^-~->~Ag_(_s_)$ Reduction

$Al_(_s_)~->~Al^+^3~_(_a_q_)+~3e^-~$ Oxidation

The reduction potential values for each half-reaction are:

$Ag_2S~+~e^-~->~Ag_(_s_)~+~S^-^2~_(_a_q_)$ - 0.69 V

$Al^+^3~_(_a_q_)+~2e^-~->~Al_(_s_)$ -1.66 V

In the aluminum half-reaction, we have an oxidation reaction, therefore we have to flip the reduction potential value:

$Al_(_s_)~->~Al^+^3~+~2e^-~$ +1.66 V

Finally, to calculate the overall potential we have to add the two values:

1.66 V - 0.69 V = 0.97 V

For the second question, we have to keep in mind that in the cell notation we put the anode (the oxidation half-reaction) in the left and the cathode (the reduction half-reaction) in the right. Additionally, we have to use "//" for the salt bridge, therefore:

$Al_(_s_)/Al^+^3~_(_a_q_)~//~Ag^+~_(_a_q_)/~Ag_(_s_)$

I hope it helps!

3 0

3 years ago

Which is more acidic among the following?

GaryK [48]

Answer:

Explanation:

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2 years ago

4. Energy can be conserved by -

mart [117]

Energy can be conserved by efficient energy use.

Answer: Option A

Explanation:

Energy can be transferred from one form to another, but it cannot be destroyed or created. So it can be conserved if efficiently used. Thus efficient usage of energy lead to conservation of energy. Due to conservation of energy, the forces can be renewable and non-renewable.

So, we should know how the input energy can be completely converted to another form of energy leading to efficient usage of energy without any loss. As if there is no loss, input energy will be equal to output energy leading to 100% efficiency.

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3 years ago