Build and Test Heat Device Practice Test

A thermos was constructed with a double wall, a vacuum layer between the walls, a reflective coating, and a tightly sealed cap. To test it, a student poured in coffee at $75^\circ\text{C}$, sealed the cap, left it in a $22^\circ\text{C}$ room, and measured the coffee temperature every 2 hours.

Data: 0 hr: $75^\circ\text{C}$, 2 hr: $72^\circ\text{C}$, 4 hr: $68^\circ\text{C}$, 6 hr: $65^\circ\text{C}$, 8 hr: $62^\circ\text{C}$.

Criterion: maintain $\ge 60^\circ\text{C}$ for 8 hours.

What is the correct evaluation of the thermos test?

Three containers were tested with the same hot water starting at $70^\circ\text{C}$ in a $22^\circ\text{C}$ room. After 1 hour, the temperatures were:

Container A (no insulation): $30^\circ\text{C}$

Container B (foam insulation): $55^\circ\text{C}$

Container C (thick foam + sealed lid): $63^\circ\text{C}$

Criterion: after 1 hour, temperature must be $\ge 60^\circ\text{C}$.

Which container(s) meet the criterion?