question_subject:
Science
question_exam:
NDA-I
stats:
0,10,21,5,8,10,8
keywords:
{'velocity': [0, 2, 2, 6], 'denser medium': [0, 1, 0, 3], 'ray': [2, 0, 5, 15], 'rarer medium': [0, 0, 0, 1], 'light': [16, 4, 34, 62], 'medium': [1, 0, 1, 11], 'denser': [0, 0, 0, 2], 'change': [0, 0, 1, 7]}