D. 20 C which is the room temperature
There are 5 valence electrons in nitrogen.
The 'North pole' of any magnet is the one that would be attracted to the Earth's North magnetic pole. In that sense, they are just labels that identify the opposite magnetic force produced at each end of the magnet. The Earth'smagnetic field also has poles, North and South. more at study.com
Gravity accelerates you at 9.8 meters per second per second. After one second, you're falling 9.8 m/s. After two seconds, you're falling 19.6 m/s, and so on.