I have a question about describing my house. I know the word is viejo for old, nuevo for new and modern is moderno. If I say Mi casa is modern do I say Mi casa is modena by changing the "o" to the feminie "a". The same for viejo if I describe my house would I change the "O" to an "a" in viejo like Mi casa es vieja.

2 answers

yes, adjectives must agree with their subjects. Since la casa is feminine, the adjectives must change o to a: nueva, vieja
Yes, but moderna, not modena