<span>Hydrogen
gas (H2) can be found in trace amounts in Earth’s atmosphere. 
a. Hydrogen is found in acids. 
b. Hydrogen gas is highly flammable.
c. Hydrogen reacts with oxygen to form water. 
These are true, but they all describe chemical properties 
of Hydrogen, not physical properties.
d. Hydrogen gas
is less dense than oxygen gas.
Yes !  This is a physical property of Hydrogen.
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Answer:
2 x 10^-8 
Explanation:
the formula of wavelength is 
the speed divided by frequency 
so you have the speed given = 3.0x10^8m/s
and frequency = 1.5×10^16 Hz
so wavelength = 3.0x10^8m/s / 1.5x10^16 Hz
 
 
        
             
        
        
        
Answer:
oh I'm so sorry I can't answer your question it has been a long time since I learned that. so I totally forgot how to do this. sorry!
 
        
             
        
        
        
<em>Answer:</em>
<em>Velocity is vector quantity.So it needs direction in addition to speed.</em>
<em>Explanation:</em>
<em>The velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time. Velocity is equivalent to a specification of its speed and direction of motion. </em>