Why does it make sense for the valence electrons to stay the same within a group?

If equal masses of the listed metals were collected , which would have a greatest volume ? a. aluminum 2.70,b.zinc7.14,c.copper 8.92,d.lead 11.34

Nitrogen dioxide decomposes according to the reaction 2 no2(g) ⇌ 2 no(g) + o2(g) where kp = 4.48 × 10−13 at a certain temperature. if 0.70 atm of no2 is added to a container and allowed to come to equilibrium, what are the equilibrium partial pressures of no(g) and o2(g)

Na chemical reaction, activation energy increases the of the reactants. this outcome causes the particles to collide, which results in the of new products.