The answer is C hope this help's.
The temoerature decreases because the average kinetic energy is always linearly related to temperature
Answer:

Explanation:
There are three heat transfers involved.
heat from combustion of propane + heat gained by water + heat gained by calorimeter = 0
q₁ + q₂ + q₃ = 0
m₁ΔH + m₂C₂ΔT + C_calΔT = 0
Data:
m₁ = 2.1 g
m₂ = 280 g
Ti = 25.00 °C
T_f = 26.55 °C
Ccal = 92.3 J·°C⁻¹
Calculations:
Let's calculate the heats separately.
1. q₁
q₁ = 2.1 g × ΔH = 2.1ΔH g
2. q₂
ΔT = T_f - Ti = 26.55 °C - 25.00 °C = 1.55 °C
q₂ = 280 g × 4.184 J·°C⁻¹ × 1.55 °C = 1816 J
3. q₃
q₃ = 92.3 J·°C⁻¹ × 1.55 °C = 143.1 J
4. ΔH

Answer:
See explanation and image attached
Explanation:
The IUPAC system of nomenclature enables the structure of molecules to be written seamlessly from the name of the compound. Hence it is commonly called the systematic nomenclature.
The parent chain here is propane. It is substituted at the 2- position by a methyl group and at the 3-position by 4-chlorophenyl group as we can see in the image attached to this answer.