Afzal Guru was executed in 2013 for his role in the 2001 Parliament attack.
Galib secured 88 per cent in the examination, the results for which were announced on Thursday.
According to Jammu and Kashmir Board of School Education (BOSE) officials, 33,893 of the 55,163 candidates qualified the examination held in November last.
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While the overall pass percentage was 61.44, more girls (64.31 per cent) passed the examination compared to boys (58.92 per cent), they said.
Congratulatory messages poured in for the 17-year-old on social media, even as friends and family made a beeline to his house in Sopore town of Baramulla district.
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"A big shout-out to Ghalib Afzal Guroo on clearing his 12th class exams with flying colours- 441 marks. Ghalib has definitely proven 'When the going gets tough, the tough get going'. All the best for the future endeavours! Rise and shine!," Sarah Hayat, spokesperson of opposition National Conference, said in a tweet.