Gypsum has the same hardness as a fingernail
That would be C because sickle cells make you very sick and could lead to death and I remember it by thinking sickle has the word sick in it.
2 and 3 because a neutron is neutral, a proton is positive, and a electron is negative. So they both have 0 and 1. (neutron and proton or electron)
<span>Co3+ is Cobalt with three electrons removed (It's positive by 3). So, the abbreviated notation for Cobalt, minus three electrons (Coming from 4s and 3d) is:
[Ar]4s1, 3d5</span>
