Question

what is the only metal that is not a solid at room temperature?
a iridium
b mercury
c gallium
d cesium

Explanation:

To determine the metal not solid at room temperature, we analyze each option:

• Iridium (a) is a solid metal at room temperature.
• Mercury (b) is a liquid at room temperature (its melting point is -38.83 °C, below typical room temp ~20 - 25 °C).
• Gallium (c) has a melting point of 29.76 °C, so it's solid at standard room temp (but melts in hand).
• Cesium (d) has a melting point of 28.44 °C, solid at standard room temp (melts near body temp).

Only mercury is liquid (not solid) at room temperature.

Answer:

b. mercury