When the block of ice is heated, it turns to water when the temperature reaches the melting point of ice 0 ∘C. After the entire block of ice turns into water, the water gets heated up and turns into vapour at 100 ∘C.
So, after 1.5 minutes, if water is still present in the vessel, the temperature will be 100 ∘C. However, if all the water has evaporated into vapour, then the temperature cannot be determined.