Answer:
+5
Explanation:
The oxidation number of phosphorus can be obtained as follows:
H4P2O7 = 0
4(+1) + 2P + 7(—2) = 0
4 + 2P —14 = 0
Collect like terms 
2P = 14 — 4
2P = 10
Divide both side by 2
P = 10/2
P = +5
The oxidation number of phosphorus is +5
 
        
             
        
        
        
Answer: 1.99 x 10²² molecules H2
Explanation:First we will solve for the moles of H2 using Ideal gas law PV= nRT then derive for moles ( n ).
At STP, pressure is equal to 1 atm and Temperature is 273 K.
Convert volume in mL to L:
750 mL x 1 L / 1000 mL
= 0.75 mL
n = PV/ RT
 = 1 atm ( 0.75 L ) / 0.0821 L.atm/ mole.K ( 273 K)
 = 3.3x10-² moles H2
Convert moles of H2 to atoms using Avogadro's Number.
3.3x10-² moles H2/ 6.022x10²³ atoms H2 / 1 mole H2
= 1.99x10²² atoms H2
 
        
             
        
        
        
Answer:
A. Encourage an increase in pollution in these countries
 
        
             
        
        
        
Answer:
Here's what I find.
Explanation:
An indicator is usually is a weak acid in which the acid and base forms have different colours. Most indicators change colour over a narrow pH range.
(a) Litmus
Litmus is red in acid (< pH 5) and blue in base (> pH 8).
This is a rather wide pH range, so litmus is not much good in titrations.
However, the range is which it changes colour includes pH 7 (neutral), so it is good for distinguishing between acids and bases.
(b) Phenolphthalein
Phenolphthalein  is colourless in acid (< pH 8.3) and red in base (> pH 10).
This is a narrow pH range, so phenolphthalein is good for titrating acids with strong bases..
However, it can't distinguish between acids and weakly basic solutions.
It would be colourless in a strongly acid solution with pH =1 and in a basic solution with pH = 8.
(c) Other indicators  
Other acid-base indicators have the general limitations as phenolphthalein. Most of them have a small pH range, so they are useful in acid-base titrations.
The only one that could serve as a general acid-base indicator is bromothymol blue, which has a pH range of 6.0 to 7.6.
 
        
             
        
        
        
X rays have a lower frequency than microwaves would be the scientific statement.