In Hope's apparatus, when water is cooled by the freezing mixture, the lower thermometer T₁ reaches 4 °C first and stays steady there for a while. This happens because:

1. As water cools toward 4 °C, its density increases and it sinks to the bottom. 2. The densest 4 °C water collects near T₁, so T₁ falls fast then stabilises at 4 °C. 3. Below 4 °C water becomes less dense and rises, so the upper thermometer T₂ then drops faster. 4. The freezing mixture is in the upper bowl, not near T₁, so the proximity option is wrong. _Source: Balbharati (Maharashtra Board) Class 10 Science & Technology, Ch 5 "Heat", p.74_