Chemical reaction, generally speaking. It's a vague definition, but it's easy to remember.
_Mg + _HCL = _MgCl2 + H2
Separate the terms on each side:
_Mg + _HCl = _MgCl2 + H2
Mg- 1 Mg-1
H-1 H-2
Cl-1 Cl-2
Mg is balanced on both sides so move on to the next (put a 1 in the space).
1Mg
There are two H's and two Cl's on the results side, so to balance the equation put a 2 as a coefficient for HCl and it'll all balance out.
2HCl
Balamced equation will be:
1Mg + 2HCL = 1MgCl2 + H2
The noble gases AKA the column with full outermost valence shells. (Group 18)
Answer:
a: chemical change because the change cannot be reversed.
b: physical change because the action can be reversed.
c: chemical change.
d:chemical change.
any change that cannot be reversed is a chemical change and any change that can be reversed is a physical change.
<h3><em><u>ᎪꪀsωꫀᏒ</u></em></h3>
even no = 3/6 = 1/2
no. less than 5 = 4/6 = 2/3