You Marie Curie assistant and your task is to study a piece of material and 2 points track its decay. You are starting with a 10kg lump of an unknown material. After 5 days you measure it again and only have 7.5kg remaining of the original material, the other 2.5kg is now something else. Can you determine the half life? If so, what is the half life of this material? O 5 days O O 10 days © 15 days 20 days​

How do you know when a chemical reaction has occurred

Estimate the molar mass of the gas that effuses at 1.6 times the effusion rate of carbon dioxide.

Select the correct value for the indicated bond angle in each of the compounds. o−o−oo−o−o angle of o3 90° 109.5° < 109.5° 120° < 120° 180° f−b−ff−b−f angle of bf3 180° < 109.5° < 120° 120° 109.5° 90° f−o−ff−o−f angle of of2 < 120° 120° 90° 109.5° 180° < 109.5° cl−be−clcl−be−cl angle of becl2 90° 109.5° 180° 120° < 109.5° < 120° f−p−ff−p−f angle of pf3 90° 109.5° < 109.5° 180° 120° < 120° h−c−hh−c−h angle of ch4 90° < 109.5° 180° 120° < 120° 109.5°