Let's examine the given chemical compounds and determine which one has the highest melting point:
1. Aluminium Carbonate ([tex]$Al_2(CO_3)_3$[/tex]):
- Aluminium Carbonate is an ionic compound. Typically, ionic compounds have high melting points due to the strong electrostatic forces between the ions. However, Aluminium Carbonate does not exist stably and decomposes into Aluminium Hydroxide and Carbon Dioxide.
2. Sucrose ([tex]$C_{12}H_{22}O_{11}$[/tex]):
- Sucrose is a molecular compound, specifically a disaccharide (table sugar). It has a relatively high melting point among molecular compounds. The melting point of sucrose is around 186-188°C.
3. Octane ([tex]$C_8H_{18}$[/tex]):
- Octane is a hydrocarbon, hence a molecular compound with weak van der Waals forces. It has a lower melting point compared to ionic compounds and some large molecular compounds. The melting point of octane is approximately -56.79°C.
4. Water ([tex]$H_2O$[/tex]):
- Water is a molecular compound held together by hydrogen bonds. It has a melting point of 0°C, which is higher than many small molecular compounds but much lower than most ionic compounds and some large molecular compounds like sucrose.
Considering the melting points of these compounds, we observe that:
- Aluminum Carbonate theoretically has the potential for high interaction strength but lacks stability.
- Sucrose has a well-documented high melting point among stable compounds listed here.
- Octane and Water have significantly lower melting points compared to Sucrose.
Based on these points, the compound with the highest melting point among the given options is Sucrose ([tex]$C_{12}H_{22}O_{11}$[/tex]). Therefore, the compound indicated by the index 2 has the highest melting point.
