Questions

The Doppler effect or Doppler shift is the change in frequency or wavelength of a wave in relation to an observer who is moving relative to the wave source. 

Superhero Batman shares a name with an oil production Batman, a town in Turkey.

FALSE. Each hemoglobin molecule can transport four molecules of oxygen.

Hemoglobin, or Hb, is a protein molecule found in red blood cells (erythrocytes) made of four subunits: two alpha subunits and two beta subunits. Heme the component of hemoglobin responsible for binding oxygen consists of an iron ion that binds oxygen and a porphyrin ring that binds the globin molecules, one molecule binds one molecule of oxygen and can bind up to four oxygen molecules.

Maglev trains are used in Japan, South Korea and China only.

Maglev derived from magnetic levitation using the principle of magnetic repulsion is a system of train transportation that uses two sets of magnets, one set to repel and push the train up off the track as in levitation then another set to move the 'floating train' ahead at great speed taking advantage of no friction. Maglev trains are therefore quieter and smoother than conventional trains, and have the potential for much higher speeds

Despite over a century of research and development, maglev transport systems are in operation in just three countries Japan, South Korea and China.

Hence Maglev -- Magnetic-levitation.