The intermolecular forces between polymer molecules are strong, so these substances are at room temperature. What word completes the sentence?

I want to say

Stronger

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.

1.solid

2.carbon dioxide

3.helium