Answer:
Equation correctly showing the heat of solution
Explanation:
Mass of aqueous solution = m = 100 g
Specific heat of solution = c = 4.18 J/gºC
Change in temperature = 
ΔT = 21.6ºC - 30.0ºC = -8.4ºC
Heat lost by the solution = Q
Q = -3,511.2 J ≈ -3.51 kJ
Heat absorbed by potassium nitrate when solution in formed; Q'
Q' = -Q = 3.51 kJ
Moles of potassium nitrate , n= 
The heat of solution =
So, the equation correctly showing the heat of solution
The answer is (C) 2 hydrogen atoms
Answer is: 25.84 milliliters of sodium metal.
Balanced chemical reaction: 2Na + 2H₂O → 2NaOH + H₂.
d(Na) = 0.97 g/mL; density of sodim.
m(NaOH) = 43.6 g; mass of sodium hydroxide.
n(NaOH) = m(NaOH) ÷ M(NaOH).
n(NaOH) = 43.6 g ÷ 40 g/mol.
n(NaOH) =1.09 mol; amount of sodium hydroxide.
From chemical reaction: n(NaOH) : n(Na) = 2 : 2 (1: 1).
n(Na) = 1.09 mol.
m(Na) = 1.09 mol · 23 g/mol.
m(Na) = 25.07 g; mass of sodium.
V(Na) = m(Na) ÷ d(Na).
V(Na) = 25.07 g ÷ 0.97 g/mL.
V(Na) = 25.84 mL.
<span>Problem 1) From the given options the one that is proper of a chemist is the option B. testing a sample of water form a well. This activity belongs to the field called analytical chemistry which uses special techniques (instruments and processes) to study (separate, identify and quantify matter).
Problem 2) The only of the given procedures that involves a physical change in one substance is the option D. grinding chalk into a fine powder. In this process the molecules remain being the same (same atoms bonded in the number and way).</span>
C. Ninhydrin is used to detect prints on a non-porous surface
