Answer:
5.25g
Explanation:
We'll begin by writing the balanced equation for the reaction. This is shown below:
Na2SiO3 + 8HF → H2SiF6 + 2NaF + 3H2O
From the balanced equation above, 
8 moles of HF reacted to produce 2 moles of NaF.
Therefore, 0.5 moles of HF will react to produce = (0.5 x 2)/8 = 0.125 mole of NaF.
Next, we shall convert 0.125 mole of NaF to grams.
This is illustrated below:
Mole of NaF = 0.125 mole 
Molar mass of NaF = 23 + 19 = 42g/mol 
Mass of NaF =..? 
Mass = mole x molar mass 
Mass of NaF = 0.125 x 42 
Mass of NaF = 5.25g
Therefore, 5.25g of NaF is produced from the reaction. 
 
        
             
        
        
        
 The answer should be  B - Nitrogen Dioxide.
 
        
             
        
        
        
Answer:
Option (D)
Explanation:
Phosphorylation can be simply defined as the addition of a phosphate group to an organic and inorganic molecule. This process helps in regulating the processes that occur in the cells. It leads to the growth and development of cells and this process is efficiently carried out with the help of enzymes like kinase. It also plays an important role in transferring the signals within the cells, synthesis, and functioning of proteins within the cells, and storing as well as releasing of energy.
Thus, the correct answer is option (D).
 
        
             
        
        
        
Redox Reaction is an ionic bond
        
             
        
        
        
Lead is a toxic metal that affects the central nervous system. A Pb-contaminated water sample contains 0.0011% Pb by mass. 13.6 × 10³ ml water contains 150 mg of Pb. 
<h3>How to calculate the mass of solution ? </h3>
Given percentage of Pb present in the sample solution is 0.0011%
That means 0.0011 grams of Pb present in the 100g of solution. 
So, 
= 
= 13.6 × 10³ g water 
<h3>What is Density ? </h3>
The mass per unit volume is called density. Density is represented as D or ρ.
It is expressed as:

where, 
ρ = Density 
m = mass of the object 
V = Volume of object 
Now put the value in above expression we get 


V = 13.6 × 10³ ml 
Thus from the above conclusion we can say that Lead is a toxic metal that affects the central nervous system. A Pb-contaminated water sample contains 0.0011% Pb by mass. 13.6 × 10³ ml water contains 150 mg of Pb. 
Learn more about the Density here: brainly.com/question/1354972
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