I think it's covalent...? Hope that helps.
I think the correct answer would be A. When a polonium atom with 84 protons, 124 neutrons, and 84 electrons undergoes alpha decay, a lead atom would be produced with 82 protons, 122 neutrons, and 84 electrons together with an alpha particle having two protons and two neutrons.
D. paper d, paper c, paper a, paper b
It is the concept of surface tension that helps the coin to float on the top of the water in the glass. The surface tension acts just opposite to the gravitational force and that is why when any metal placed in the water it will float and come on the surface. Hope this helps!
