The number of atoms present in carbon, specifically Carbon-12, is the number of atoms present in 1 gram of the substance. One moles of the substance weighs approximately 12.01 g/mole. The unit suggests that every mole of carbon weighs 12.01 grams. 
        
             
        
        
        
The question is improperly formatted.
What is the concentration of H+ ions in a 2.2 M solution of HNO3.
Answer:-
2.2 moles of H+ per litre
Explanation:-
  M stands for molarity. 2.2 M means 2.2 moles of HNO3 is present per litre of the solution.
 Now HNO3 has just 1 H in it's formula. HNO3 would give H+. So 2.2 moles of HNO3 would mean 2.2 moles of H+ per litre.
 
        
             
        
        
        
Answer:
The area of the given rectangular index card = <u>9677.4 mm²</u>    
Explanation:
Area is defined as the space occupied by a two dimensional shape or object. The SI unit of area is square metre (m²).
<u>The area of a rectangle</u> (A) =  length (l) × width (w) 
Given dimensions of the rectangle: Length (l) = 5.0 inch, Width (w) = 3.0 inch
Since, 1 inch = 25.4 millimetres (mm)
Therefore, l = 5 × 25.4 = 127 mm, and w = 3 × 25.4 = 76.2 mm
Therefore, <u>the area of the given rectangular index card</u> = A= l × w = 127 mm × 76.2 mm = <u>9677.4 mm²</u>
 
        
             
        
        
        
Obviously since plant cell contains chloroplasts.