Out of the listed effects of a major solar storm, the most likely ones are

Statement 1 is correct. A solar storm can disrupt the Earth's ionosphere, which can affect the signal transmission of GPS and other radio-based navigation systems.

Statement 3 is correct. Strong currents induced by the solar storm in power grids can damage transformers and cause widespread blackouts.

Statement 4 is correct. Solar storms can energize particles in the Earth's magnetosphere, leading to spectacular auroras at lower latitudes than usual.

Statement 6 is correct. The drag from a solar storm can alter the orbits of satellites, especially those in lower Earth orbit.

Statement 7 is correct. Similar to GPS, radio communication can be affected by disturbances in the ionosphere.

Statement 2 is incorrect. Tsunamis are caused by underwater earthquakes or volcanic eruptions, not solar storms.

Statement 5 is incorrect. While a solar storm could potentially ignite some fires through electrical sparks, this is not a widespread effect.

Therefore, codes 2 and 5 should not form the part of answer.