Answer: C
Explanation: Amplitude controls loudness, and frequency controls pitch. The more frequent the higher pitch.
 
        
                    
             
        
        
        
The question is incomplete, the complete question is;
The compound magnesium phosphate has the chemical formula Mg3(PO4)2. In this compound, phosphorus and oxygen act together as one charged particle, which is connected to magnesium, the other charged particle. What does the 2 mean in the formula 5Mg3(PO4)2? A. There are two elements in magnesium phosphate. B. There are two molecules of magnesium phosphate. C. There are two magnesium ions in a molecule of magnesium phosphate. D. There are two phosphate ions in a molecule of magnesium phosphate.
Answer:
There are two phosphate ions in a molecule of magnesium phosphate.
Explanation:
The compound magnesium phosphate is an ionic compound. Ionic compounds always consists of two ions, a positive ion and a negative ion.
In this case, the positive ion is Mg^2+ while the negative ion is PO4^3-.
The subscript, 2 after the formula of the phosphate ion means that there are two phosphate ions in each formula unit of magnesium phosphate.
 
        
             
        
        
        
Answer: Matter is how much space or opacity an object takes up. In short anything that take up space. Things like balls, trees, and even people are all made of matter. Mass is how much matter a object has. Air also has mass also, even though we can't see it. Things like cars, buildings, even planets have mass.
Explanation: Paragraphs are sometimes 4-6 sentences.
 
        
             
        
        
        
Answer:
Single replacement
Explanation:
A reaction in which one element replaces a similar element is called single replacement.  In this case, C is replacing A.
 
        
                    
             
        
        
        
Answer:
The displacement in t = 0,  
y (0) = - 0.18 m
Explanation:
Given f = 40 Hz , A = 0.25m , μ = 0.02 kg / m, T = 20.48 N 
v = √ T / μ 
v = √20.48 N / 0.02 kg /m = 32 m/s
λ = v / f 
λ = 32 m/s / 40 Hz = 0.8 
K = 2 π / λ 
K = 2π / 0.8 = 7.854 
φ = X * 360 / λ 
φ = 0.5 * 360 / 0.8 = 225 ° 
 Using the model of y' displacement 
y (t) = A* sin ( w * t - φ )
When t = 0
y (0) = 0.25 m *sin ( w*(0) - 225 )
y (0) = 0.25 * -0.707
y (0) = - 0.18 m