When the calculation (2.31)(4.9795x10^3)/(1.9971x10^4) is performed, how many significant digits should be reported for the answer?

How do i complete this electrolysis of water lab? i’m at home, so i don’t have the materials, and the lab didn’t properly work and was incomplete at school.

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

Which type of precipitation would most likely form when the surface air temperature is slightly below freezing and the air temperature increases as you move upward away from the ground?