Answer:
because you are a living organism. you also have feeling.
H-1 only has 1 proton and 1 electron, so its mass number is 1.
H-2 has one more neutron so its mass number is 2
H-3 has one more neutron than H-2 so its mass number will be 3.
average atomic mass = 1 x 99% + 2 x 0.8% + 3 x 0.2%
=1.012
Less plankton would mean that all the organisms that eat plankton would start to die off because they have no source of energy.
You know if it's endothermic or exothermic by doing the enthalpy reaction. If the change of temperature is negative then it is exothermic, while positive is endothermic.
If you get -22K then its exothermic, but if you get +22 its endothermic.
