Answer:
Things that sink:
Key
Money.
Rock
Spoon
Crayon
Button
Marble
Comb
Clip
Pine cone
Things that float:
Leaf
Feather
Cork
Pencil
Rubber duck
Bottle cap
Apple
Toothpick
Boat
People
Explanation:
To be more scientifically accurate, you must be more specific in your questions (and answers, people!) to describe your parameters exactly. At the right mass per unit volume (e.g., dust vs a rock) talc will either sink or float. In the right configuration, 80.000 tons of steel might float or it might sink faster than most rocks (e.g., a battleship vs the Brooklyn Bridge.) Even the “little things” need to be considered, such as water tension effects (e.g., a water-strider insect vs a frog.)
Your question could be far more accurately answered if it were worded as “What are 10 objects that float … sink in water, if they are (e.g.) 10g perfect cubes while the objects and water are at 25 C.” (Yes, this eliminates water ice, which is an outlier, so you could make a special provision for it in your question if that’s important.)
