$\}$

$A,DG,H$

$B,DE,F$

$AI$

$\{HJ$

Identify all candidate keys for $R2.$

ABD is the candidate key, because closure of ABD has all the attributes of $R.$ Prime attributes: A B D$,$ Non$-$prime attributes: C E F G H I

Check out that $R2$ is in $3NF$ or not? If not decompose it in $3NF.$

$(1)--$ Neither $AB$ is super key, nor $C$ is prime attribute.

$(2)--$ Neither AD is not super key, nor GH is prime attribute.

$(3)-$ Neither BD is not super key, nor EF is prime attribute.

$(4)-$ Neither $A$ is not super key, nor I is prime attribute.

$(5)-$ Neither $H$ is not super key, nor $J$ is prime attribute.

So$,R2$ is not in $3NF$ as it is not following the rules of $3NF.$

Therefore, R$2($A$,$B$,$C$,$D$,$E$)$ needs to be divided into following:

$R21(ABCI)$

$R22(ADGHJ)$

$R23(BDEF)$

$R24(ABD)$

R$211($A B C$)$

R$212($A I$)$

R$221($A D G H$)$

R$221($H J$)$