3. When neither air masses can overpower each other and may not move for a long time.
1) warm front
2)cold front
3)occluded front
4)stationary front

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).

a electronegativity decreases beacuse the size of nucleus is bigger.