The 3 indicates the third electron shell. (Which has only 1 electron in it in this configuration)
Hope this helps! :)
Answer;
The above statement is true
upon heating a copper sample will expand, leading to a lower density
Explanation;
-The density of solids decreased with increase in temperature and vice versa. The increase in temperature causes the volume of the solid to increase which as a result decreases the density as Density=Mass/Volume. The temperature of a body is the average kinetic energy of the molecules present in it.
In other words; The temperature of a body is the average kinetic energy of the molecules present in it. Therefore; when heat is supplied ( or temperature is increased) the average kinetic energy increases which increases the volume and thus density decreases.
Yo sup??
we can solve this problem by applying Newton's 2nd law
F*t=Δp
p=momentum
pi=mu=1500*30
pf=mv=m*0=0
Therefore
F*3=1500*30
F=15000 N
Hope this helps.
They have low boiling points