How many moles of gas are in a system at STP that has a volume of 30 L?

Iknow the answer to 13 is b and 14 is d. i just need to know why the correct answers are correct

Read the claim. breakfast is an important meal. it jump starts the body’s process of using calories to break down food. appetite can decrease with age, but going too long without eating causes metabolism to slow down. current research shows that incorporating legumes such as lentils and chickpeas into meals boosts metabolism for twenty-four hours. who might benefit from this claim? people who have a fast metabolism stores that sell exercise equipment people who take vitamin supplements grocery stores that sell legumes

Using the periodic table, complete the following. element: hydrogen symbol: h₂ molecular weight: g mass of one mole: g/mol