Help pls even if u can only answer 1

What is limiting reactant? with examples

Significant figures are digits read directly from the measuring instrument plus one more digit, which is __ by the observer.

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