Nouns ending in -ence are usually feminine.
The suffix forms abstract nouns, often from verbs.
Is conscience masculine or feminine?
laconscience
The rule behind it
97.6% of -ence nouns are feminine
In context
Même les enfants doivent prendre conscience du monde.
Even children need to make sense of the world.
Sa conscience s'est soudainement réveillée en lui.
His conscience suddenly awoke in him.
J'avais conscience qu'il manquait quelque chose.
I was conscious that something was missing.