Question

question 5

1. to assist in heat dissipation exhaust valves are filled with ....

a. water
d. vacuum
c. mercury
b. sodium

Explanation:

Exhaust valves operate at very high temperatures. Sodium has a high thermal conductivity and melts at a relatively low temperature (around 98°C), then circulates within the hollow valve to efficiently transfer heat away from the valve head to the cooler valve stem, aiding heat dissipation. Water would boil and cause pressure issues, mercury is toxic and has high density, and a vacuum would not conduct heat effectively for this purpose.

Answer:

b. sodium