What's the summary of matter

In a closed or isolated system , matter can not be created or destroyed. it can change forms but is conserved true or false

Which of the following units is not an official si unit

The diagin dilutepage 6 of 12a6a5(a)fluorine, chlorine, bromine and iodine are placed in the same group of theperiodic table.state the common name used to describe elements in this group.(i)state the group in which the elements are placed and explain whythey are placed in that group.(ii)which of the above named elements is a solid at roomtemperature and pressure?