What is not a dissolved gas present in the ocean a carbon dioxide b hydrogen c oxygen d nitrogen

The correct answer is option B, hydrogen.

The majority of the atmospheric gases are found in the sea water solution. In supplementation to oxygen and nitrogen, the most profusely found gas in the atmosphere, that is, carbon dioxide is found in the ample concentrations in the ocean waters.  

However, hydrogen is not present, and if found it is found in minute concentration. Of the gases, nitrogen is the most abundant gas found in seawater, while oxygen is the second most abundant, and carbon dioxide is the most soluble gas, and one of the various constituents, which influences the pH balance of the ocean.  

when the displaced particles are perpendicular to the direction the wave travels, is called a transverse wave, whereas in longitudinal wave the displace practices are parallel to the direction of the wave.

in the given image:

first image shows - longitudinal wave

second image shows - transverse wave

third image shows - longitudinal wave

fourth image shows - longitudinal wave