Answer:
My wife gave me a hundred rupees, (but/however) I can't find it.
He bought a house and it's near the zoo. (It could also be) He bought a house near the zoo.
I wanted to buy the car (but/however) it was costlier than my house.
Explanation:
You could use either but or however for the first and last question because the second sentence is contradicting the first sentence. For the second question you could have it both ways, but I recommened using the first way, (He bought a house and it's near the zoo.) because it uses a clause.
