Use table 1: analysis of decay in the laboratory guide to answer this question: scientists find a piece of wood that is thought to be from an ancient fire circle. they find that the wood contains an amount of carbon-14 (14c) that is approximately 1/16 of the current atmospheric 14c levels. determine approximately how many years ago the tree was chopped down to be used for the firewood. if you started with 1 million carbon-14 atoms, how many atoms would remain in the wood? 14c has a t1/2 of 5,750 years.
why is 14c dating a good method to use for dating a human leg bone but not so good a method for dating a dinosaur bone? you may have to check the dates of the existence of humans and dinosaurs on earth on a chart showing the geological eras.
potassium-40 (40k) is a radioactive material that decays into argon-40 (40ar). the half-life of a sample of 40k is 1.3 billion years. rocks containing 40k have been around since the formation of the earth, and 40ar gas has been accumulating in those rocks since the earth formed. however, when rocks are heated by volcanic action, all the 40ar leaves the rock when the gases escape. create a scenario and discuss, based on your knowledge of half-life, the value of potassium-argon dating to geologists.

If 10.0 ml of the solution on the right are withdrawn from the 100 ml beaker and diluted again in a similar manner, what is the new concentration? m nacl

Straightforward questions answered in the powerpoint slidesreaction: heating the starting materials under refluxwhat does it mean to heat under reflux? why do we choose water as the reflux solvent? what are boiling chips used for? why do we put a condenser on top of the reaction? why do we add heat and let the reaction stir for 30 minutes? why do we add sulfuric acid to the reaction after it cools as opposed to when it’s still hot? separation: filtration of precipitatewhy don’t we do an aqueous and organic extraction in the separatory funnel? why do you rinse the salicylic acid on the filter with ice cold water? purification: recrystallization of salicylic acid (no hot filtration needed)what is the difference in the amount of room temperature water vs. boiling water needed to dissolve the salicylic acid (assume a 1.2 gram yield of salicylic acid)? remember, in the lab if you need x ml of boiling water to dissolve a solid, then you should add a little more (definitely no more than 1.5 times the theoretical amount) to ensure it doesn’t recrystallize prematurely.analysis: melting point of salicylic acidwhat can you conclude if the melting point of the salicylic acid you just synthesized is 152-155oc and the 1: 1 mix of your product and “synthetic” salicylic acid is 151-154oc?

Which explanation is true about what happens to a ray of light when it strikes a mirror? a. a light ray is transmitted toward a mirror at a certain angle. the light ray is then reflected by the mirror at an equal angle but in the opposite direction of the transmitted ray. b. an incident ray strikes a mirror at an angle with a line perpendicular to the mirror. the light ray is then reflected at an angle equal to the angle of incidence but on the opposite side of the perpendicular line. c. a reflecting ray strikes a mirror at an angle with a line perpendicular to the mirror. the light ray is then refracted at an angle equal to the angle of the reflecting ray and on the same side of the perpendicular line. d. an incident ray strikes a mirror at an angle with a line parallel to the mirror. the light ray is then transmitted at an angle equal to the angle of incidence but on the opposite side of the parallel line. you so much! : -d take the time to try and answer correctly.