Which one of the following looks odd---------?

K2CrO4

O4

H2S

KMnO4

Which one of the following looks odd---------?

10th-class-mcqs-all-subjects9th-class-mcqs-all-subjects11th-class-mcqs-past-papers12th-class-macqs-past-paperscss-islamiat-past-papers-mcqsnts-online-test-preparation