Answer:
B. Ca(NO2)2
Explanation:
Ions (charged atoms) combine with one another to form stable ionic compounds. In this case, calicium ion (Ca2+) is said to react with NO2, which has a charge of -1 i.e. +1-1(2) = 1-2 = -1. 
This means that calcium has a charge of +2 while nitrite ion has charge of -1, hence, when they combine, they exchange their charges, which become their subscript as follows:
Ca2+ + NO2- → Ca(NO2)2
Ca(NO2)2 is a stable ionic compound called calcium nitrite. Notice that it takes two atoms of NO2- to react with one atom of Ca2+.
 
        
             
        
        
        
The relation between the volume of the gas and the temperature is established by Charles's law. With a decrease in the temperature, the volume decreases by 45.7 mL. Thus, option c is correct.
<h3>What is Charle's law?</h3>
Charle's law states the direct relation present between the temperature and the volume of the gas. The law is given as:
V₁ ÷ T₁ = V₂ ÷ T₂
Given,
V₁ = 50 mL
T₁ = 303.15 K
T₂ = 277.15 K
Substituting the value the final volume is calculated as:
50 ÷ 303.15 = V₂ ÷ 277.15
V₂ = (50 × 277.15) ÷ 303.15
= 45.71 mL
Therefore, option c. 45.7 mL is the final volume.
Learn more about Charles law here:
brainly.com/question/16927784
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Answer:
d and e
Explanation:
We have 5 solutions with different molar concentrations, that is, the quotient between the number of moles of solute and the liters of solution. This can be expressed as mol/L or M. The most dilute would be the one having the less number of moles of solute per liters of solution, that is, solution d or e, which have the same concentration. If we order them from the most diluted to the most concentrated, we get:
d = e < a < b < c