Which metal in period 5 is very reactive and has two valence electrons in each atom?
rubidium (rd)
strontium (si)
zirconium (z1)
silver (ag)

The right answer is A, that is Rubidium (Rb)

Explanation:

Strontium has 2 electrons in the valance shell and is alkaline earth metal but relatively reactive.

Rubidium comes in period 5 and under alkali metals and very reactive towards oxygen and highly reactive than strontium  and other option

This element has 2 electrons in its valence subshell (5s) according to Madelung rule.

Madelung rule that if the two orbitals have the same n+l value they fill in increasing order of n.

So the right answer is A, that is Rubidium (Rb)

answer: the rate of diffusion increases with increase in temperature.

increase in temperature, increases the molecular/particles speed (kinetic energy. diffusion means movement of particles through the material.

generally, the heavier the particle the more it interacts with the environment and more the temperature matters. so higher temperature results in higher diffusion.

1. a)c-14 has two more protons

2. d)they have different numbers of protons, neutrons, and valence electrons; they are all gases at room temperature.

3. c) iron and nickel.