Answer:
For number 2, your answer is C. 
Explanation:
The nucleus is positively charged because the proton is positive and a neutron is neutral. An electron has a negative charge.
 
        
             
        
        
        
Answer:
The maximum mass of carbon dioxide that could be produced by the chemical reaction is 70.6gCO_{2}
Explanation:
1. Write down the balanced chemical reaction:

2. Find the limiting reagent:
- First calculate the number of moles of hexane and oxygen with the mass given by the problem.
For the hexane:

For the oxygen:

- Then divide the number of moles between the stoichiometric coefficient:
For the hexane:

For the oxygen:

- As the fraction for the oxygen is the smallest, the oxygen is the limiting reagent.
3. Calculate the maximum mass of carbon dioxide that could be produced by the chemical reaction:
The calculations must be done with the limiting reagent, that is the oxygen.

 
        
             
        
        
        
B. Troposphere, stratosphere, mesosphere, thermosphere
        
             
        
        
        
Answer:
<h3>The answer is option A</h3>
Explanation:
To find the number of moles in a substance given it's number of entities we use the formula

where n is the number of moles 
N is the number of entities
L is the Avogadro's constant which is 
6.02 × 10²³ entities
From the question we have

We have the final answer as
<h3>2.99 moles</h3>
Hope this helps you