Answer:
Reaction A:
- Hydrogen atoms in H₂ are oxidized.
- Oxygen atoms in O₂ are reduced.
- Hydrogen gas H₂ is the reducing agent.
- Oxygen gas O₂ is the oxidizing agent.
Reaction B:
- Oxygen atoms in KNO₃ are oxidized.
- Nitrogen atoms in KNO₃ are reduced.
- Potassium nitrate (V) KNO₃ is both the oxidizing agent and the reducing agent.
Explanation:
- When an atom is oxidized, its oxidation number increases.
- When an atom is reduced, its oxidation number decreases.
- The oxidizing agent contains atoms that are reduced.
- The reducing agent contains atoms that are oxidized.
Here are some common rules for assigning oxidation states.
- Oxidation states on all atoms in a neutral compound shall add up to 0.
- The average oxidation state on an atom is zero if the compound contains only atoms of that element. (E.g., the oxidation state on O in O₂ is zero.)
- The oxidation state on oxygen atoms in compounds is typically -2. (Exceptions: oxygen bonded to fluorine, and peroxides.)
- The oxidation state on group one metals (Li, Na, K) in compounds is typically +1.
- The oxidation state on group two metals (Mg, Ca, Ba) in compounds is typically +2.
- The oxidation state on H in compounds is typically +1. (Exceptions: metal hydrides where the oxidation state on H can be -1.)
For this question, only the rule about neutral compounds, oxygen, and group one metals (K in this case) are needed.
<h3>Reaction B</h3>
Oxidation states in KNO₃:
- K is a group one metal. The oxidation state on K in the compound KNO₃ shall be +1.
- The oxidation state on N tend to vary a lot, from -3 all the way to +5. Leave that as
for now. - There's no fluorine in KNO₃. The ion NO₃⁻ stands for nitrate. There's no peroxide in that ion. The oxidation state on O in this compound shall be -2.
- Let the oxidation state on N be
. The oxidation state of all five atoms in the formula KNO₃ shall add up to zero.
. As a result, the oxidation state on N in KNO₃ will be +5.
Similarly, for KNO₂:
- The oxidation state on the group one metal K in KNO₂ will still be +1.
- Let the oxidation state on N be
. - There's no peroxide in the nitrite ion, NO₂⁻, either. The oxidation state on O in KNO₂ will still be -2.
- The oxidation state on all atoms in this formula shall add up to 0. Solve for the oxidation state on N:
. The oxidation state on N in KNO₂ will be +3.
Oxygen is the only element in O₂. As a result,
- The oxidation state on O in O₂ will be 0.
.
The oxidation state on two oxygen atoms in KNO₃ increases from -2 to 0. These oxygen atoms are oxidized. KNO₃ is also the reducing agent.
The oxidation state on the nitrogen atom in KNO₃ decreases from +5 to +3. That nitrogen atom is reduced. As a result, KNO₃ is also the oxidizing agent.
<h3>
Reaction A</h3>
Apply these steps to reaction A.
H₂:
O₂:
H₂O:
- Oxidation state on H: +1.
- Oxidation state on O: -2.
- Double check:
.
.
The oxidation state on oxygen atoms decreases from 0 to -2. Those oxygen atoms are reduced. O₂ is thus the oxidizing agent.
The oxidation state on hydrogen atoms increases from 0 to +1. Those hydrogen atoms are oxidized. H₂ is thus the reducing agent.
Answer:
a) Na
c) Na
b) Sr
d) Ca
Explanation:
As we move from left to right across the periodic table the number of valance electrons in an atom increase. The atomic size tend to decrease in same period of periodic table because the electrons are added with in the same shell. When the electron are added, at the same time protons are also added in the nucleus. The positive charge is going to increase and this charge is greater in effect than the charge of electrons. This effect lead to the greater nuclear attraction. The electrons are pull towards the nucleus and valance shell get closer to the nucleus. As a result of this greater nuclear attraction atomic radius decreases and ionization energy increases because it is very difficult to remove the electron from atom and more energy is required.
As we move down the group atomic radii increased with increase of atomic number. The addition of electron in next level cause the atomic radii to increased. The hold of nucleus on valance shell become weaker because of shielding of electrons thus size of atom increased.
As the size of atom increases the ionization energy from top to bottom also decreases because it becomes easier to remove the electron because of less nuclear attraction and as more electrons are added the outer electrons becomes more shielded and away from nucleus.
Trace evidence can end up transferring to the crime scene through Locard's Exchange Principle, which states that whenever two things come into contact with one another, there is an exchange of physical material A.K.A evidence. This exchange is most often done through physical contact, such as a struggle or a suspect attempting to hide evidence or alter the crime scene. It can even involve a suspect's shirt sleeve brushing against some wet paint.
I hope I helped!
4) would be your correct answer