During a camping trip, sierra collected dry branches and broke them into smaller pieces. she then placed the sticks in a fire pit and used a match to light the sticks on fire. next, she propped a metal pan of water over the fire and heated it until the water boiled. which list correctly describes physical and chemical changes that occurred in this scenario? physical change: breaking sticks chemical changes: lighting the fire, boiling water physical change: boiling water chemical change: breaking sticks, lighting the fire physical changes: lighting the fire, boiling water chemical change: breaking sticks physical changes: breaking sticks, b

The answer is D.  physical changes: breaking sticks, boiling water

chemical change: lighting the fire             i just took the test hehe ;)

nanotechnology is a powerful tool in biomaterials research as it creates numerous possibilities for the engineering of functional molecules. nano-bio refers to projected ability to incorporate biomimicry into various materials at nanoscale.  

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%