Need a lot of help with these chem calculations

What neutral atom is isoelectronic to mn+4

Three cards with holes are arranged in a straight line. a light is shined through the first card’s hole and travels through all three cards. what does this tell you about light rays? a) that light is reflected b) that light is refractive c) that light travels in a straight line d) that light does not travel in a straight line

What metric units would you use to measure the thickness of a key