Answer:
have the same number of atoms of each element in the reactants and in the products
Explanation:
<em>The basic principle in balancing a chemical equation would simply be to have the same number of atoms of each element in the reactants and in the products.</em>
<u>A balanced chemical equation is one that has the same number of atoms of each element on the reactant and the product's side of the equation.</u> For example, consider the equation below:

On the reactant's side, there are 2 atoms of H and O while there are 2 atoms of H and 1 atom of O on the product's side. This is an imbalanced equation. In order for it to be balanced, the number of atoms of H and O on the reactant side must be equal to the number of H and O on the product side as below.

Answer is B.
As the diaphragm contracts and flattens, it increases the volume of the thorax where the lungs are located. This results in a decrease in pressure (Boyle’s Law, if you know it) that creates a pressure gradient from outside to inside. This is what causes air to move into the lungs.
If the crucible wasn't covered with a lid the reactants may have produced a gas that was released into the surroundings, or mass may have been lost in the form of water vapour.
Answer:
The yearly release of
into the atmosphere is
.
Explanation:

Annual production of CaO = 
Moles of CaO :

According to reaction, 1 mole of CaO is produced along with 1 mole of carbon-dioxide.
Then along with
of CaO moles of carbon-dioxide moles produced will be:
of carbon-dioxide
Mass of
moles of carbon-dioxide:

The yearly release of
into the atmosphere is
.