18.The octet rule tells us that in every chemical
reactions, elements will either gain or lose electrons to attain the noble gas electron
configuration. This stable<span> electron configuration is known as the octet configuration
since it is composed of 8 valence. Oxygen’s electron configuration is 1s2 2s2
2p4. So when</span> oxygen reacts with
other elements to form compounds, it completes the octet configuration by
taking 2 electrons from the element
it reacts with
19. Actually pure metals are made up not of
metal atoms but rather of closely packed cations (positively charge particles).
These cations are then surrounded by a pack of mobile valence electrons which
drift from one part of the metal<span> to
another. This is called metallic bond.</span>
20. This is the
energy which is needed to break a single bond. When the dissociation energy is
large, this means that the compound is more stable. Since carbon to carbon
bonds have high dissociation energy, therefore they are not very reactive.
21. Network solids are type of solids
in which the atoms are covalently bonded to one another, so they are very
stable. It takes higher temperature to melt them because breaking these
covalent bonds required greater energy. Some examples are:
- Diamond
<span>-Silicon Carbide</span>
Answer:
Bacterial species are typified by their diversity. There are three notable common traits of bacteria, 1) lack of membrane-bound organelles, 2) unicellular and 3) small (usually microscopic) size.
Explanation:
What Are the Characteristics Common to All Bacteria?
Single-Celled. Perhaps the most straightforward characteristic of bacteria is their existence as single-celled organisms. ...
Absent Organelles. ...
Plasma Membrane. ...
Cell Walls. ...
DNA.
<u>Answer:</u> The 
for the reaction is -1052.8 kJ.
<u>Explanation:</u>
Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.
According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.
The given chemical reaction follows:
The intermediate balanced chemical reaction are:
(1) 
(2) 
The expression for enthalpy of the reaction follows:
![\Delta H^o_{rxn}=[1\times \Delta H_1]+[1\times (-\Delta H_2)]](https://tex.z-dn.net/?f=%5CDelta%20H%5Eo_%7Brxn%7D%3D%5B1%5Ctimes%20%5CDelta%20H_1%5D%2B%5B1%5Ctimes%20%28-%5CDelta%20H_2%29%5D)
Putting values in above equation, we get:
Hence, the for the reaction is -1052.8 kJ.
3. Conducts electricity in aqueous solution.
Answer:
Number of boxes = 4
Explanation:
Given:
Mass of one box of jello = 250 grams
Total quantity want to purchase = 1 kg = 1 × 1,000 gram = 1,000 grams
Find:
Number of boxes in 1,000 grams = ?
Computation:
Number of boxes = Total quantity want to purchase / Mass of one box of jello
Number of boxes = 1,000 / 250
Number of boxes = 4
Therefore, 4 boxes of jello must be purchase to get 1 kg of Jello.
