Hey there!:
Detailed solution is shown below ask if any doubt :
Physical because it is still H2O
The second and first one but if it isn’t 2 choices then 1
The concentration of mixed solution = 0.5 M
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Further explanation
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Given
0.5 M HCl
0.5 M Ca(OH)₂
Required
The concentration
Solution
Molarity from 2 solutions :
Vm Mm = V₁. M₁ + V₂. M₂
m = mixed solution
V = volume
M = molarity
V = mixed volume
1 = solution 1
2 = solution 2
Vm = V₁+V₂
Equal volumes⇒V₁=V₂, and Vm = 2V, then equation becomes :
2V.Mm = V(M₁+M₂)
2V.Mm = V(0.5+0.5)
Mm=0.5 M
B An enclosed pendulum is not acted on by air resistence or gravity. Plus, pendulum's in clocks are electronic (I think) so that's why it keeps moving back in forth. (at least i think so)