A reaction in which heat is evolved is an exothermic reaction while a reaction in which heat is absorbed is an endothermic reaction.
In the first case; Na2CO3 + H2SO4, we can see that this is an acid - base reaction therefore it is a neutralization reaction. Since the tube was hot after reaction, heat is given off so it is exothermic.
In the second case; NaOH + H2SO4, we can see that this is an acid - base reaction therefore it is a neutralization reaction. We are told that the tube is not hot but we don't know the initial temperature of the tube or if it was colder than it's initial temperature so we can not make any inference regarding whether the reaction is endothermic or exothermic.
Lastly, the reaction, NaCl + HC2H5OH does not occur so we mark "no reaction". We are told that the tube is not hot but we don't know the initial temperature of the tube or if it was colder than it's initial temperature so we can not make any inference regarding whether the reaction is endothermic or exothermic.
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They can be classified as metals.
Complete Question
Use the fact that 
to determine how much the pressure must change in order to lower the boiling point of water by a small amount 3.20e-01 K. You may assume that the entropy and density of the liquid and gas are roughly constant for these small changes. You may also assume that the volume per molecule of liquid water is approximately zero compared to that of water vapor, and that water vapor is an ideal gas. Useful constants: Atmospheric pressure is 101300 Pa The boiling point of water at atmospheric pressure is 373.15 K The entropy difference between liquid and gas per kilogram is 6.05e 03 J/kgK The molecular weight of water is 0.018 kg/mol. (a) 0.00e 00 Pa (b) 1.14e 03 Pa (c) 6.85e 26 Pa (d) 4.24e 05 Pa (e) 3.81e 28 Pa
Answer:
Correct option is B
Explanation:
From the question we are told that:
Given Equation
Change of boiling point \triangle 
Generally the equation for Change in time is mathematically given by
Where
And
(from ideal gas equation)
Therefore
Therefore correct option is B
