The answer is C.
Here’s a picture, if you need it.
Answer:troposphere
Explanation:The troposphere is the layer that holds 80 percent of the total gas in the atmosphere.
Answer:
Reaction A, B, E and F are exothermic reactions.
Explanation:
Exothermic reactions are defined as the reactions in which energy of reactants is more than the energy of the products. In these reactions, energy is released by the system.
The total enthalpy of the reaction 
comes out to be negative.
Endothermic reactions are defined as the reactions in which energy of products is more than the energy of the reactants. In these reactions, energy is absorbed by the system.
The total enthalpy of the reaction comes out to be positive.
So, from the given option reaction which are exothermic are with negative value that enthalpy of reaction and those are:
1) 
,ΔH = -1203 kJ/mol
2)
,ΔH =-176 kJ/mol
3) 
,ΔH = -393.5 kJ/mol
4) 
,ΔH =-891 kJ/mol
C.) pink <span>In a </span>base<span>, with a pH> 8.2, we would expect the </span>indicator<span> to turn </span>pink. Phenolphthalein<span> is colorless in an acidic or neutral </span>solution<span>; it turns from pink to fuchsia in a basic </span>solution<span>. Cleaners and </span>products<span> containing soaps, are </span>bases<span>.</span>
<h3><u>Answer;</u></h3>
= 78 g of NaOH
<h3><u>Explanation;</u></h3>
Concentration = Moles of solute/Volume of solution
Thus;
Moles of the solute = Volume × Concentration
= 7.80 Moles/L × 0.250 L
= 1.95 moles
But; 1 mole of NaOH = 40.0 g
Thus;
Mass of NaOH = moles × molar mass
= 1.95 moles × 40 g/mole
<u> = 78 g of NaOH</u>
