Convert the speed of light 3.0x10^8 m/s to km/day

What type of light does this light bulb produce most (i.e. at what wavelength does the spectrum have maximum intensity)?

Considering only the earth's rotation, determine how much later the asteroid would have had to arrive to put the explosion above helsinki at longitude 25˚ e? this would have obliterated the city.

The sound level near a noisy air conditioner is 70 db. if two such units operate side by side, the sound level near the, would bea. 70dbb. 73 dbc. 105 dbd 140 db