1. which of these is the balanced equation for this reaction?
a. v2o5 + hcl ? vocl3 + h2o
b. v2o5 + hcl ? 2vocl3 + 3h2o
c. v2o5 + 3hcl ? 2vocl3 + h2o
d. v2o5 + 6hcl ? 2vocl3 + 3h2o

2. __n2 + __o2 + __h2o ? __hno3
what coefficient values will balance the reaction?
a. 2,5,2,4
b. 2,2,2,2
c. 2,2,1,2
d. 1,3,1,2

3.the chemical formula of a compound can tell you -
a. the proportions of elements in the compound.
b. the three-dimensional structure of the compound.
c. the type and arrangement of bonds in the compound.
d. the properties of the elements in the compound.

4.the reaction equation below shows the formation of aluminum oxide. which set of coefficients balances the equation? al + o2 ? al2o3
a. 1,1,1
b. 2,3,5
c. 2,4,5
d. 4,3,2

5.which of the following is the balanced equation for this process?
a.2nh4no3? 2n2 + o2 + 4h2o
b. nh4no3? n2 + 3o2 + h2o
c.2nh4no3? n2 + o2 + 3h2o
d.2nh4no3? n2 + 3o2 + 2h2o

1) The answer is D. V2O5 + 6HCl = 2VOCl3 + 3H2O.

V2O5 + HCl = VOCl3 + H2O

V=2                       V=1
0=5                       O=3
H=1                        H=2
Cl=1                       Cl=3

The equation is not balanced because on the left side there is 2 vanadium (V) atoms, 5 oxygen (O), 1 hydrogen (H) and 1 chlorine (Cl) atoms. In the right side, there is 1 vanadium (V) atom, 3 oxygen (O), 2 hydrogen and 3 chlorine (Cl) atoms. 
To balance the chemical equation we need place a coefficient of 6 in front of HCl,  a coefficient of 2 in front of VOCl3 and coefficient 3 of in front of H2O.

2) The answer is A.2,5,2,4

2N2(g) + 5O2(g) + 2H2O = 4HNO3(aq)

This is a redox reaction because there has been a change in the oxidation states of nitrogen and oxygen, and it has to be balanced over half-reaction method:

N⁰ ⇒ N⁺⁵ + 5e⁻  / x2
2e⁻ + O⁰ ⇒ O⁻² / x5

2N⁰ ⇒ 2N⁺⁵ + 10e⁻ 
10e⁻ + 5O⁰ ⇒ 5O⁻²

Now it only remains to count how many hydrogens miss.

3) The chemical formula of a compound can tell you - A.the proportions of elements in the compound.

Chemical formulas are the symbols of chemical compounds, the form of displaying their molecules; in addition to the qualitative composition, they also show the quantitative ratio of the atoms constituting the molecule of the chemical compound. Formulas are expressed by chemical symbols; for example. molecules of the chemical compound of water are composed of two hydrogen atoms and one oxygen atom, so the molecular formula is H2O water.

4) The answer is D.4,3,2.

4Al + 3O2 = 2Al2O3

This is a redox reaction because there has been a change in the oxidation states of aluminum and oxygen, and it has to be balanced over half-reaction method:

Al⁰ ⇒ Al⁺³ + 3e⁻  / x4
4e⁻ + O₂⁰ ⇒ 2O⁻² / x3

4Al⁰ ⇒ 4Al⁺³ + 12e⁻  
12e⁻ + 3O₂⁰ ⇒ 6O⁻² 

5) The answer is A. 2NH4NO3 = 2N2 + O2 + 4H2O

This is a redox reaction because there has been a change in the oxidation states of nitrogen and oxygen, and it has to be balanced over half-reaction method:

N⁺⁵ + 5 e⁻ ⇒ N⁰ 
N⁻³ ⇒ N⁰ + 3 e⁻
O⁻²  ⇒ O⁰ + 2 e⁻

In the reaction, there are 2 species of nitrogen N⁺⁵ and N⁻³, the first is reduced and the second oxidized.