Chemistry knowledge riddle time!
Thread Content
Turning chemical knowledge into riddles can increase the fun of learning chemistry and enhance memory. Now please fill in the answers to the following riddles in the blanks: (1) Called a treasure, it truly is a treasure; animals and plants cannot do without it； It’s invisible and intangible, and its density decreases as one goes higher. (Guess the name of this substance) ______ (2) It forms a semicircle; when ignited, it produces blue flames ； Killing without bloodshed, pursuit with no trace. (Guess a substance name)______
(1) Oxygen (2) Carbon monoxide
(1) Oxygen (2) Carbon monoxide
(1) Oxygen (2) Carbon monoxide