Oxygen (
O
) has three naturally occurring isotopes:
16
O
,

17
O
,
and
18
O
.

16
O
is the most abundant isotope with an abundance of
99.757
%
and an isotopic mass of
15.995
u.
The second most abundant isotope is
18
O
with an abundance of
0.205
%
and an isotopic mass of
17.999
u.
The least abundant isotope,
17
O
,
has an abundance of only
0.038
%
and an isotopic mass of
16.999
u.

Calculate the average atomic mass of oxygen.

Naoki's bicycle has a mass of 10 kg. if naoki sits on her bicycle and starts pedaling with a force of 168 n, causing an acceleration of 2.8 m/s2, what is naoki's mass?

Achemical reaction (also known as a chemical change) produces substances that are chemically different from the starting materials. an example of a chemical reaction is the formation of water from hydrogen and oxygen gas.in a physical change, a substance changes its physical appearance but not its chemical identity. an example of physical change is the formation of liquid water from solid water, a familiar process called melting. physically, liquid water looks very different from solid water (ice) but the chemical identity, water, is the same for both. which of following changes that affect the composition of our atmosphere involve physical changes and which involve chemical reactions? oxygen gas changes to ozone during thunderstorms carbon dioxide is produced by the combustion of gasoline in an automobile engine. when coal, oil, and natural gas are decomposed in landsills they produce methane gas. freezing rain develops when a warm air mass overrides a cold air mass. fog forms from water vapor when the temperature drops below the dew point

Melting and boiling are endothermic processes. this means that these processes absorb energy from their surroundings in order to occur. use this information and the data you collected in the phase change gizmo to describe what happens to the temperature of water when you boil it, then explain why this result occurs.