Answer:
0.299 moles of PCl5
Explanation:
First form an equation based of given information: P4 + Cl2= 4PCl5
Next balance it: P4 + 10Cl2 = 4PCl5
Take your given value (53.0g of Cl2) and divide it by its molar mass to get moles of Cl2: 53.0g/70.906g = 0.747 moles Cl2
Then, multiply by the molar ratio (10Cl2 to 4PCl5): (0.747 x 4 mol PCl5)/10 mol Cl2 = 0.299 moles PCl5
Answer: Mg is the excess reactant for the forward reaction.
Explanation: It is a stoichiometry problem and solved with the help of given grams and using balanced equation. Grams of both the reactants are converted to moles and divided by their coefficients. The excess reactant is the one for which we get the highest number on doing above steps.
The balanced equation is:

Molar mass of silicon tetra chloride is 169.9 gram per mol and the molar mass of Mg is 24.3 gram per mol.

= 

= 2.67 mol Mg
From balanced equation, the coefficient of silicon tetra chloride is 1 and that of Mg is 2. So, we will divide the moles of silicon tetra chloride by 1 and that of Mg by 2 and see which one gives highest number.
For silicon tetra chloride,
= 0.317
and for Mg,
= 1.34
The highest number is for Mg and so the excess reactant for the forward reaction is Mg.
Keeping your arm straight in front of you, you rotate 90° to your left, and see the left side of the circle lit while the right side is dark. Half the ball is still lit up, but you can see only part of the lit area. As you continue to rotate, you see a different amount of the ball.
The mass of
is 0.185 g.
To calculate the number of moles first calculate the molar mass of
.

Molar mass of nitrogen and oxygen is 14 g/mol and 16 g/mol respectively
Thus, 
Now, number of moles can be calculated from mass and molar mass as follows:

Therefore, number of moles of 0.185 g
is 0.0042 mol.
Answer:
1. a chemical reaction in which one substance breaks up into two or more new substances: decomposition reaction
2. a reaction in which two or more substances combine to form a new substance: synthesis reaction
3. the reaction of an acid with a base to form a salt and water: neutralization reaction.
4. chemical compound formed when the negative ions from an acid combine with the positive ions of a base: salt
5. two ionic compounds reacting in solution to form two new compounds, one of which is insoluble: double displacement reaction.
6. a reaction in which an active metal displaces a less active metal or hydrogen from a compound solution (or a nonmetal replaces a nonmetal from a compound in solution): Single replacement reaction
Explanation:
1. Decomposition is a type of chemical reaction in which one reactant gives two or more than two products.
Example: 
2. Synthesis reaction is a chemical reaction in which two reactants are combining to form one product.
Example:
3 and 4. Neutralization is a chemical reaction in which an acid and a base reacts to form salt and water. Salt is formed when cations or positive ions of base combine with anions or negative ions of acid.
Here
is the salt formed by combination of
from base and
from acid.
Example: 
5. A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.
Example: 
6. Single replacement reaction is a chemical reaction in which more reactive element displaces the less reactive element from its salt solution.
Example: 