What mass of water freezes if 5.43 kJ oh heat are released in the process

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

How many atoms are there in 5.70 mol of mg

What are the advantages of using the metric system? designed as a decimal system making conversions simpler more accurate system of measurement has prefixes that correspond to an amount to use with all base units used by the entire scientific community