Answer:
Pb(NO3)2 – Lead(II) nitrate sourceaà
Other names: Lead nitrate source Plumbous nitrate source Lead dinitrate source
Appearance: White colourless crystals asource:White or colourless crystals source.
H2O – Water, oxidane source
Other names: Water (H2O) source: Hydrogen hydroxide (HH or HOH) source: Hydrogen oxide source
Appearance: White crystalline solid, almost colorless liquid with a hint of blue, colorless gas source.
 
        
             
        
        
        
The answer is 
option D "CO." Co also known as 
Cobalt is the 27th element on the periotic table. It was discovered in <span>1735, it's boiling point is 3200 k.</span>
Atomic mass: 58.9332
Protons: 27
Neutrons: 32
Electrons: 27
Hope this helps!
 
        
        
        
Answer: A) Storing experimental samples
Explanation:
 It is a common piece of laboratory glassware that can be made of glass or plastic and is opened at the top and closed at the bottom.
 It cannot be used for measurements because there is no graduation indicating the volume.
 Althought it can contain extra chemicals left over from an experiment, it is not the main proposal of the glassware that is to store samples.
 It cannot be used in a microscope and the object for that is a microscope slide.
 
        
             
        
        
        
Answer:- oxygen.
Explanations:- The electronic configuration is given and we are asked to figure out the electrically neutral atom that will have the electron configuration,  .
 .
The sum of electrons for this electron configuration is 8. If we look at the periodic table then 8 is the atomic number of oxygen. 
So, the electrically neutral atom for the given electron configuration is oxygen.
 
        
             
        
        
        
Answer:
Total partial pressure, Pt = 821 mm Hg
Partial pressure of Helium, P1 = 105 mm Hg
Partial pressure of Nitrogen, P2 = 312 mm Hg
Partial pressure of Oxygen, P3 = ? mm Hg
According to Dalton's law of Partial pressures,
Pt = P1 + P2 + P3
So, <u>P3 = 404 mm Hg</u>