What object is metal and has high density

Iknow #2 is d. i just need to know why

21. consider the following chemical reaction: n2+ o2 2 no if 10.0 g of n2 reacts with excess oxygen then how many grams of no can be formed? a) 10.7 g b) 21.4 g c) 32.9 g d) 42.8 g page 4 of 8

An unknown substance has been shown to have metallic bonds. which of the following is most likely a property of this substance? a. low conductivity b. low boiling point c. high malleability d. high solubility in water