172- In a container that is thermally insulated, there is a piece of ice at zero degrees Celsius. If we add 800 grams of water at 50 degrees Celsius to the container, then bring it to thermal equilibrium, 100 grams of ice remains in the container. How many grams was the initial piece of ice? $$\left(C_{\text{water}} = 4200\ \frac{\text{J}}{\text{kg}\cdot\text{K}} \text{ and } L_f = 336000\ \frac{\text{J}}{\text{kg}}\right) \text{ (only heat exchange between water and ice)}$$ (1) $300$ (2) $400$ (3) $500$ (4) $600$
\textbf{172-} In a container that is thermally insulated, there is a piece of ice at zero degrees Celsius. If we add 800 grams of water at 50 degrees Celsius to the container, then bring it to thermal equilibrium, 100 grams of ice remains in the container. How many grams was the initial piece of ice?
$$\left(C_{\text{water}} = 4200\ \frac{\text{J}}{\text{kg}\cdot\text{K}} \text{ and } L_f = 336000\ \frac{\text{J}}{\text{kg}}\right) \text{ (only heat exchange between water and ice)}$$
\begin{center}
(1) $300$ \hspace{2cm} (2) $400$ \hspace{2cm} (3) $500$ \hspace{2cm} (4) $600$
\end{center}