Because when the cells divide (resulting in more cells) the multicellular organism mantains its strong cells and when one cell is damaged the other cells compensate for that damaged cell.
Lifting the backpack off the floor. Force is being applied in only one direction then (up) which is what constitutes as work. Carrying the box of crayons applies force in two directions (up and forward), which cancel each other out. Work has a vector, which is a quantity containing both direction and magnitude (one, finite direction, not two).
It would be 7 because the acid and base cancel out each other
2
refer to periodic table for explanation