The main difference between gases and liquids is that in gases a. the molecules are moving faster b. the forces between molecules are greater c. the distance between molecules are greater d. the molecules collide more frequently

c- cold periods in earth's history during which glaciers covered much of the surface.

explanation:

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.

idk what is it? is this a question that you know the answer or u dont

answer is: nuclear fusion produces elements that are heavier than helium.

nuclei combine to form a heavier nucleus, releasing energy.  

for example, fusion of hydrogen atoms at the sun.  

this fusion nuclear reaction is in the inner core of the sun and hydrogen (atomic number 1) is conveted into helium (atomic number 2).  

the inner core is the central region of the sun and all solar energy is produced in the core by nuclear fusion.