Those would be called indicators , simply google them and you should find many. I'll leave some examples "bromophenol blue"  "Methyl red" and "phenol red".
        
             
        
        
        
Answer:
 is the total pressure of the tank.
 is the total pressure of the tank.
Explanation:
Partial pressures of nitrogen = 
Partial pressure of oxygen =  
Total pressure of gases in the tank = P
Applying Dalton's law of partial pressures :


 is the total pressure of the tank.
 is the total pressure of the tank.
 
        
             
        
        
        
<span>Charles' law says "at a constant pressure, the volume of a fixed amount of gas is directly proportional to its absolute temperature".
V </span>α T 
Where V is the volume and T is the temperature in Kelvin of the gas. We can use this for two situations as,
V₁/T₁ = V₂/T₂
V₁ = 2.00 L
T₁ = 40.0 ⁰C = 313 K
V₂ = ? 
T₂ = 30.0 ⁰C = 303 K
By applying the formula,
2.00 L / 313 K = V₂ / 303 K                   
                   V₂ = (2.00 L / 313 K) x 303 K
                   V₂ = 1.94 L
Hence, the volume of the balloon at 30.0 ⁰C  is 1.94 L
        
             
        
        
        
Answer:
<u>C) 4</u>
Explanation:
<u>The reaction</u> :
- C (s) + 2H₂ (g) ⇒ CH₄ (g)
        12g      4g             16g
Hence, based on this we can say that : <u>2 moles of hydrogen gas are needed to produce 16g of methane.</u>
<u />
<u>For 32g of methane</u>
- Number of moles of H₂ = 32/16 × 2
- Number of moles of H₂ = <u>4</u>
 
        
                    
             
        
        
        
0.012moldm⁻³
Explanation:
Given parameters: 
Mass of AgNO₃  = 1000mg 
Volume of water = 500mL 
Unknown: 
Molarity of solution  = ? 
Solution: 
The molarity of a solution is the number of moles of a solute dissolved in volume of solvent. 
  Molarity = 
  
Number of moles of AgNO₃  = ? 
    Number of moles = 
Molar mass of AgNO₃ = 108 + 14 + 3(16) = 170g/mol
    convert mass to g; 
       1000mg = 1g 
  Number of moles  =  = 0.00588moles
  = 0.00588moles 
    convert the given volume to dm³; 
        1000mL  = 1dm³; 
         500mL = 0.5dm³
Now solve; 
   Molarity =  = 0.012moldm⁻³
  = 0.012moldm⁻³
learn more: 
Molarity brainly.com/question/9324116
#learnwithBrainly