Which sentence about particles in matter is true?
a. atoms are present in solids and liquids but not gasses
b. the particles of matter are in constant motion
c. the same kinds of atoms found in different element
d. when a solid changes to a liquid, the sizes of the particles change

B, because its a simple matter (puns lol) of the fact that all matter is moving, just some moves slower than others.

Answer;

B. The particles of matter are in constant motion

Explanation;Matter is anything that has weight and occupies space. It occurs in three states namely, gases, liquids and solids.All matter is made up of tiny particles that are in constant motion.According to kinetic theory of matter, matter is made of many particles, that is atoms or molecules, that are in constant motion. In gases, the motion of particles are in constant random motion, they move freely. In liquids, the motion is constrained by the liquid's volume, while in solids the motion of particles is greatly constrained to a small space.

A.(nh4)(2co3)is the correct answer 

12 is probably the typical age for a first kiss but i think its to young.