How to remember the first 20 elements of the periodic table?

At 300 mm hg, a gas has a volume of 380 l, what is the volume at standard pressure

How many moles of lead are in 1.50 x 10^12 atoms of lead? could you explain the answer as well and not just give it to me i am refreshing for finals and i need to know how to do it

Gusing the milligrams of ascorbic acid you entered above, the ratio of total sample volume to aliquot volume, and the total milligrams of the vitamin c tablet that you dissolved, calculate the mass of ascorbic acid in the vitamin c tablet for each trial. do this by scaling up to find the amount (mg) of ascorbic acid in your 250 ml flask. enter your calculated mass of ascorbic acid in the vitamin c tablet, for each trial. be sure to enter your calculated mass in the corresponding order that you entered your milligrams of ascorbic acid. the milligrams of ascorbic acid you entered for entry #1 previously should correspond to the mass of ascorbic acid that you enter for entry #1 here.