#1. a salt crystal has a mass 0.14mg, how many nacl formula units does it contain? express your answer using two significant figures. #2. how to write sodium carbonate and lead (ii) nitrate as a complete ionic equation and as a net ionic equation?

Explain which group an element with the electron configuration 1s2 2s2 2p6 3s2 3p6 3d1 4s2 belongs to.

What is the most important factor in determining climates.

Before it was launched, a helium-filled balloon had a pressure of 201 kpa at a temperature of 27°c. at an altitude of 15,000 m, the pressure had decreased to 2.5 kpa and the temperature had dropped to -14 °c. the volume of the balloon increased to 59.3 m3. what is the original volume of the balloon? 13 m3 0.85 m3 0.077 m3 1.17 m3