I think the answer is that is lights up?
Answer:
Heat of fusion
Explanation:
The heat required to change 1 gram of a solid at its normal melting point to a liquid at the same temperature is called the heat of fusion.
The formula for the heat of fusion is given by :

Where
n is no of moles
is molar heat of the substance
Hence, the correct answer is heat of fusion
Answer is: the percent by mass of NaHCO₃ is 2,43%.
m(NaHCO₃) = 10 g.
V(H₂O) = 400 ml.
d(H₂O) = 1 g/ml.
m(H₂O) = V(H₂O) · d(H₂O).
m(H₂O) = 400 ml · 1 g/ml.
m(H₂O) = 400 g.
m(solution) = m(H₂O) + m(NaHCO₃).
m(solution) = 400 g + 10 g.
m(solution) = 410 g.
ω(NaHCO₃) = 10 g ÷ 410 g · 100%.
ω(NaHCO₃) = 2,43 %
14 since K has 1 valence but there’s two so 2 valence for k and oxygen has 6 but there’s two so 12