Answer:

Explanation:
Hello.
In this case, since this is a system in which the water is heated up and the metal is cooled down in a calorimeter which is not affected by the heat lose-gain process, we can infer that the heat lost by the metal is gained be water, it means that we can write:

Thus, in terms of masses, specific heats and temperatures we can write:

Whereas the equilibrium temperature is the given final temperature of 28.4 °C and we can compute the specific heat of the metal as shown below:

Plugging the values in and since the density of water is 1.00 g/mL so the mass is 80.0g, we obtain:

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Answer:
copper metal and steel metak
It is believed that the entire solar system was born f<span>rom an early nebula.</span>
Answer:
(B) HNO3 + NaOH
Explanation:
Hello,
In this case, for the production of sodium nitrate a substance having the sodium as a cation should react with another substance having the nitrate anion. Moreover, neutralization reactions are carried out when bases react with acids, such is the case of nitric acid and sodium hydroxide:

Thus, the answer is (B) HNO3 + NaOH as the other options involve salts rather than acids or bases as starting reactants.
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