I don't have a toothpick to see if cakes are done, can i use a chopstick?

Now that's thinking creatively!  But, I wouldn't go the chopstick route, and here's why:  a chopstick is quite large in diameter.  If your cake is underdone, something that thick poked into and removed from the center could cause the cake to quickly fall.  A better choice would be a thin wooden skewer (think skewered appetizers), a wooden cocktail pick or a piece of uncooked thin spaghetti (yes, you read correctly).  Just like a toothpick, if it comes out clean, the cake is done.  Any clinging batter or crumbs means more time in the oven is needed.  Experienced bakers can touch the cake top lightly with a clean finger and when the cake springs back with little indent, know it's done.  Here are more handy Tips for Making Cakes - bake on!