The atomic number of the element indicated by the model is 8, corresponding to option 'C' in the question.
<span>Some solutions demonstrate colligative properties, which rely on the quantity of solute in a solvent. To find the elevation in boiling point, we use the formula:
</span><span>ΔT(boiling point) =
(Kb)mi
where Kb represents a constant, m is the solution's molality, and i is the van't Hoff factor.
From the provided information, we can easily determine i as follows:
</span>ΔT(boiling point) = (Kb)mi
103.45 - 100 = (0.512)3.90i
i = 1.73 <-------van't Hoff factor
Step

: To find the mass of a single washer, divide the total measured mass by the number of washers

. Step

: Convert kilograms to milligrams knowing

; thus

resulting in the final answer

.
The scenario that would lead to an endothermic ΔHsolution is when |ΔHsolute| > |ΔHhydration|. Explanation: A solution is characterized as a homogeneous mixture of two or more substances that can exist in gas, liquid, or solid forms. The enthalpy of solution may either be positive (indicating an endothermic reaction) or negative (indicating an exothermic reaction). Enthalpy represents the heat released or absorbed during the dissolution process at constant pressure. The initial step of this process involves separating the solute, which breaks all the intermolecular forces binding the solute together. This separation is an endothermic process, requiring energy to disrupt these interactions. Therefore, ΔH1 is positive. Consequently, for this situation to result in an endothermic reaction, the enthalpy of the solute must exceed the enthalpy of hydration.
The accompanying illustration depicts the structure of dimethyl terephthalate. Explanation: Dimethyl terephthalate, whose chemical formula is C6H4 (COOCH3) 2, is a diester derived from terephthalic acid and methanol. It appears as a white solid. Another method of syntheses involves p-xylene and methanol, characterized by an oxidation process followed by esterification.