If the word EARTH is written as QPMZS in coded form, how can HEART be written following the same coding?

HEART is written as SQPMZ.

In EARTH to QPMZS each letter has a fixed substitute.

E maps to Q, A maps to P, R maps to M, T maps to Z, H maps to S.

Read these substitutes for the letters of HEART.

H=S, E=Q, A=P, R=M, T=Z = SQPMZ.