Answer is (4).<span>
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<span><em>Explanation:</em>
</span><span>
<span>The given mixture contains an </span>insoluble solid<span> <span>and an </span></span>aqueous solution of salt. <span>The insoluble solid is </span>sand. <span>
First </span><span>we have to separate </span>insoluble solid. <span>Sand can be separated by doing </span>filtration. When we filter the mixture sand can be seen as the residue on the filter paper.
<span>After filtering the mixture, we should collect the </span>filtrate. <span>Filtrate is the </span>salt solution. <span>By doing </span>evaporation <span>we can get the </span>solid salt. <span>
First </span>and second choices are wrong <span>because </span>after evaporating water filtration
cannot be done and salt and sand will be mixed together.<span>
Salt cannot be
filtered out because the salt is soluble and it is <span>in
aqueous medium. Hence, third choice is wrong</span></span></span>
<span>Temperature is defined as the rate at which molecules move or vibrate
</span>
- Telleurium ( Te) is the chemical symbol
- electron is 52,
- there are 2 electron in 5s
Answer:
This means the the sign of q for the reaction was _NEGATIVE _____ and the reaction was _EXOTHERMIC_____.
Explanation:
In calorimetry, when heat is absorbed by the solution, the q-value of the solution will have a positive value. This means that the reaction will produce heat for the solution to absorb and thus the q-value for the reaction will be negative. This is an exothermic reaction.
Whereas, when heat is absorbed from the solution, the q-value for the solution will have a negative value. This means that the reaction will absorb heat from the solution and so the reaction is endothermic, and q value for the reaction is positive.
So, from the question, since the q-value of water is positive, it means that heat is absorbed by the solution and the reaction will produce a negative value of q and it's an exothermic reaction because the reaction produces heat for the solution.
Preparing 15 mg/gl working standard solution from a 20 mg/dl stock solution will require the application of the dilution principle.
Recalling the principle:
initial volume x initial molarity = final volume x final molarity
Since we were not given any volume to work with, we can as well just take an arbitrary volume to be prepared. Let's assume that the stock solution is 10 mL and we want to prepare 15 mg/gl from it:
Applying the dilution principle:
10 x 20 = final volume x 15
final volume = 200/15
= 13.33 mL
This means that in order to prepare 13.33 mL, 15 mg/l working standard solution from 10 ml, 20 mg/dl stock solution, 3.33 mL of the diluent must be added to the stock solution.
More on dilution principle can be found here: brainly.com/question/11493179
