Hey there!
Molar mass N2 = 28.01 g/mol
Therefore:
28.01 g N2 -------------- 6.02*10²² molecules N2
( mass N2 ?? ) ----------- 25,000 molecules N2
mass N2 =  ( 25,000 * 28.01 ) /  ( 6.02*10²³ ) 
mass N2 = 700250 / 6.02*10²³
mass N2 = 1.163*10⁻¹⁸ g 
Hope that helps!
 
        
                    
             
        
        
        
Answer: I belive the answer is A
Explanation:
 
        
             
        
        
        
Balanced chemical reaction: A + 5C ⇄ AC₅.
<span>[A] = 0.100 M; equilibrium concentration.
</span><span>[C] = 0.0380 M.
</span>[AC₅] = 0.100 M.
Kf = [AC₅] / ([A] · [C]⁵).
Kf = 0.100 M ÷ (0.100 M · (0.0380 M)⁵.
Kf = 12620658.54 = 1,26·10⁷.
<span>The formation constant can be calculated when </span>chemical equilibrium is reached, when the forward reaction rate is equal to the reverse reaction rate.
        
             
        
        
        
Answer:
The correct answer is: X is nitrogen dioxide, and Y is a metal oxide
Explanation:
Combustion of compound of containing nitrogen and metal will give nitrogen  dioxide and metal oxide as product. During combustion reaction a compound reacts with oxygen in order to yield oxides of elements present in the compound.
The general equation is given as:

Hence, the correct answer is :X is nitrogen dioxide, and Y is a metal oxide.
 
        
             
        
        
        
You would know that the variable is quantitative if it shows any number to express the quantity. For example, quantitative variables are 50°C, 5 atm, 2 moles, 100 L and so on. A variable is qualitative if it expresses a relative quantity but not expressing a number. Examples would be: few, too hot, several, or even describing the characteristics of a variable. Hence, when the variable is in grams, then that would be quantitative.