Help please ASAP just with number 8

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

Given the following reaction: c3h8+5o2=3co2+4h20 how many grams of co2 will be produced 7 g of c3h8 and 98 g of o2

What does the mass of 0.7891 mol of ferric oxide (fe2o3)