Yes all metals including Lithium, are denser than air.
No. The alkali metals in particular have very low densities; the only elements with a lower density than lithium at room temperature are the ones that are gases. Carbon, sulfur, bromine and iodine are all denser than all the alkali metals and several of the alkaline earth metals. Iodine is denser than aluminium and titanium.
Yes, cold air does have a higher density than warm air. For example, if you turn on the fireplace, all of the warm air rises to the ceiling. On the floor, the air is cooler.
No. Like all metals (with the exceptions of lithium and sodium) copper is denser than water.
No. For example, a kilogram of water is lighter than a ton of marzipan. If you mean is water denser than everything than the answer is still no. Many substances including nearly all metals and minerals are denser than water.
Virtually all metals and most other elements. Rocks etc. Countless materials are denser than perspex (1.8g/cm3)
The question is deeply flawed. Many metals are denser than many liquids, but many liquids are denser than some metals (and then, of course, there's mercury, which is both a metal and a liquid at room temperature). If all you know about two substances is that one is a liquid and one is a metal and you're forced to bet your life on which is denser ... your odds are probably SLIGHTLY better betting on the metal.
Neon, ammonia, methane, hydrogen, helium and water vapour are the best lifting gases and are all less denser than air.
No everything is layered in density, water is much more dense than air. The whole planet is organized based on density with the core being the most dense and the exosphere being the least dense.
All moons are denser that earths atmosphere
Yes because it has milk, sugar and other ingredients which all are denser than water.
The composition of Earth's atmosphere is mostly nitrogen, carbon dioxide, and oxygen. All of these elements are denser than helium, and therefore it tends to rise.
All planets, except Saturn.