Answer:
Electrons are much smaller in mass
Explanation:
Although similar in mass, protons are positively charged, while neutrons have no charge. Therefore, the number of neutrons in an atom contributes significantly to its mass, but not to its charge. Electrons are much smaller in mass than protons, weighing only 9.11 × 10−28 grams, or about 1/1800 of an atomic mass unit.
Alveoli are found in lungs and exchamge O2 and Co2 !!
so answer is last one !!
An organism that cannot make its own food is called a heterotroph. All animals and species of fungi, along with some types of bacteria, are heterotrophs.