What is the key characteristic of an oxidation–reduction reaction?

a. electricity is gained.

b. electricity is lost.

c. electrons are exchanged.

d. electrons are gained.

e. electrons are lost.

The key  characteristic  of oxidation-  reduction   reaction  is electrons   are  exchanged  ( answer  C)

   Explanation

Example  of oxidation - reduction  reaction is

  CH4  +2O2 →   CO2  + 2H2O

  from reaction above C  atom  is oxidized  from  oxidation state -4  to 4.

   On the  other hand O atoms   are reduced  from oxidation state of 0 to  2-.  therefore   there is exchange  of electrons  between  C atoms  and O atoms.

.

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.