<span> We look for
evidence. There are numerous natural phenomenon that we can't observe
happening in real-time because they happen over large time scales, or
large spatial scales. But we can observe the effects of these
phenomenon and make predictions about what other effects we should see. </span>
Answer:
1) False
2) False
3) True
4) True
5) False
Explanation:
1. Two sigma bonds comprise a double bond: False
Two sigma bonds are not possible between two atoms . There will always be one pi bond or two bonds with one sigma bond
2. A triple bond consists of one pi bond and two sigma bonds.
Two sigma bonds are not possible between two atoms . There will always be one pi bond or two bonds with one sigma bond
3. Bonds formed from atomic s orbitals are always sigma bonds. True
There is always an head to head overlapping possible with s orbital
4. A pi bond restricts rotation about the sigma-bond axis.
True.
5. A pi bond consists of two pairs of electrons.
False
Each bond can have one pair of electrons
Answer:

Explanation:
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In this case, when solid calcium carbonate, CaCO3 (s), is decomposed by the action of thermal energy (heat), solid calcium oxide, CaO (s) and carbon dioxide gas, CO2 (g) are yielded via the following reaction:

However, since calcium carbonate is solid as well as calcium oxide and carbon dioxide is given off as a gas, we write:

Which also balanced.
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Use the ideal gas law PV = nRT and manipulate it to solve for n. PV/RT = n.
Convert to SI units:
660ml -> 0.660 L
27 degrees -> 300 K
Leave Pressure as is
Use 62.36368 for R becuase you are using mmHg for Pressure.
Now plug into the equation to get about 0.025928 mols. Divide the 3.30 grams by the mols to get about 127 g/mol.