<h2>Answer : Option C) Joseph is observing the color of the reaction mixture to see whether proteins are present in the given solution.</h2><h3>Explanation :</h3>
An example of qualitative observation is the one where one uses the five senses to identify the changes in the reaction.
Here, when Joseph is studying a reaction mixture he is trying to observe a color change which will confirm that there is proteins present in the reaction mixture or not If there is a color change observed then it will confirm the presence of proteins.
Usually qualitative observations are those which can be easily predicted by using five senses.
Answer:
Mass, temperature, and phase.
I think temperature because the higher the temperature of a given quantity of a substance, more is its thermal energy. Similarly, for the same temperature, higher mass of a substance will contain more thermal energy.
The balanced chemical reaction is:
<span>2H2+O2-->2H2O
</span>
To determine the mass of hydrogen that is needed, we need use the initial amount of oxygen and relate it to hydrogen from the reaction given. We do as follows:
192 g O2 ( 1 mol O2 / 32 g O2) ( 2 mol H2 / 1 mol O2 ) ( 2.02 g H2 / 1 mol H2 ) = 24.24 g H2
It will float, because it is almost weighs like a pen.
