Potassium-40 has a half-life of 1.277 x 109 years. After 1.022 x 1010 years, how much potassium-40 will remain from a 500.3-g sample?

A. approximately 1.95 g

B. approximately 3.91 g

C. approximately 62.54 g

D. approximately 71.47 g

The amount of energy required to move an electron from one energy level to the next higher one is known as

Match each organ with the correct organ system. 1. spinal cord endocrine system 2. blood vessels lymph system 3. kidneys cardiovascular system 4. lymph nodes nervous system 5. adrenal glands excretory system 6. uterus reproductive system

Why is it important to know if a substance is a mixture or pure substance?

Assuming the density of 3% h2o2 is 1.00g/ml, what mass of h2o2 is in a 1.00ml sample? how many moles is this?

Why do scientists need governmental funding?

HNO3 + H2O > H3O (aq) + NO3 - (aq)

What do you get when you mix lemons with gunpowder

What is the mass of 9.92*10^24 molecules of methanol?

How many moles of h2so4 are required to react with 6.80 miles of al2o3

Which explanation best describes a wave? A. a disturbance that travels through a medium with a transfer of energy and matter B. a disturbance that travels through a medium without a transfer of energy and matter C.