When copper sulfate and zinc metal interact, an atom of zinc replaces an atom of copper while the sulfate molecule, made of 5 atoms, is unchanged. There are 7 atoms before and 7 atoms after the interaction. Why is this?
a
b
According to the equation presented, this answer is actually incorrect and there should be 5 atoms before and 6 atoms
after
According to the rule of chemical equations, the number 7 must be on the reactants and the products side every single
time.
According to the law of conservation of matter, the number of atoms must be conserved in an interaction, and there
are five atoms in sulfate, one copper atom, and one zinc atom to make a total of seven atoms. Therefore, there must
also be seven atoms after the interaction.
C С

russian is not my first language, so i'm afraid i can't write out an answer in russian, but hopefully you can find a way to do so. here's my best translation of the problem: you're given a plot of a particle's position in one-dimensional space over time, and you're asked to find either the total distance traveled by the particle after 6 seconds had elapsed, or the total displacement of the particle after 6 seconds.

if you want the total distance traveled, you would first need to determine the particle's velocity as a function of time, then integrate that over the 6-second interval. we know the position function is quadratic with roots at 0 and 6, so we have

where is unknown. because the position is parabolic, there is symmetry about the midpoint at , and we know that

so that the position function is

which means the velocity is

then the total distance traveled is

so the total distance traveled is 20 m.

on the other hand, if you want to find displacement: the particle starts at and ends at , so its displacement is 0.

magnets not strong enough

explanation: