Answer:
Explanation:
Endothermic reactions absorb energy from the surrounding, but exothermic reactions release energy to the surrounding.
Explanation:
Atomic number , protons and electrons have the same value / their value is same .
But for the neutron there is no specific technique. You have to remember the neutrons of every element
Answer:

Explanation:
The equation for density is:

We plug in the given values:

