Answer:

Explanation:
Hello!
In this case, when two substances at different temperature are put in contact and an equilibrium temperature is attained, we can evidence that the heat lost by the hot substance (metal) is gained by the cold substance (water) and we can write:

Which can be also written as:

Thus, since we need the specific heat of the metal, we solve for it as shown below:

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I am positive it is solar energy
Answer:
473 year
Explanation:
Using integrated rate law for first order kinetics as:
Where,
is the concentration at time t
is the initial concentration
Given:
To reach 12.5% of reactant means that 0.125 of
is decomposed. So,
= 0.125
t = ?
t = 473 year
Answer:

Explanation:
Hello!
In this case, since calcium's oxidation state when forming ionic bonds is +2 and sulfur's oxidation state when bonding those bonds is -2, for the required formula we write:

Now, since they have the same charge number, we infer the ionic compound formed when they bond is calcium sulfide:

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<u>Answer:</u> Mixture can be separated into its components but impure substance cannot be separated into components.
<u>Explanation:</u>
A mixture is defined as a combination of two or more different substances in which the component substances are individually distinct. The substances can be separated by physical processes. The separation dos not involve any chemical process because no new substance is being formed.
Impure substance is defined as a substance which can be mixture of elements, compounds or elements and compounds. The substances cannot be separated by physical means but can only be separated by chemical means.