When 500. mL of a 1.8 M solution of X is combined with 500. mL of a 1.8 M solution of Y, the resulting solution has a concentration of 0.60 M Y and 0.60 M Z. No more of substance X remains in the flask. 1. How many moles each of X and Y are present before the reaction occurs

Hind limbs will typically be stronger than forelimbs. For some animals this is because they are used for self-defense (a horse or donkey kicking, for example). Forelimbs are not going to be as strong and are often used for feeding oneself, and not intended to be as weight bearing in many mammals.