The answer is a cause this uses commutative property the fraction can be turned around but still me the same thing
second-period class average:
55+70+450+480+170+270+95 = 1590
1590/20 = 79.5
sixth-period class average:
65+225+480+595+270+190 = 1825
1825/20 = 91.25
on average, students in the sixth period class scored higher
A double replacement reaction occurs when the ionic parts of two ionic compounds are exchanged.
Reaction 1 results in a product which is a single compound. No ionic parts are exchanged.
Reaction 3 results in one compound being separated into its elemental parts. No ionic parts are exchanged.
Reaction 4 has two reactants, but Pb is an element and not an ionic compound. No ionic parts are exchanged.
Hence, the answer is Reaction 2. Both NaBr and Ca(OH)2 are ionic compounds. Br - is the anion in NaBr, and (OH)2 is also an anion. Ionic parts are exchanged.
It should be nine do you need to show work cause that's kinda hard to put it in words
