Does the law of conservation of mass contradict Islamic creed, and does one become an infidel by studying it or solving problems based on it, especially with its definitions stating that matter is neither created nor destroyed?

The statement that matter neither perishes nor is created except by the power of Allah is correct and does not entail disbelief, as long as it is qualified by Allah's will and power. However, stating unequivocally that it neither perishes nor is created (meaning it is uncreated) is false. There is no sin in solving academic problems; rather, the sin lies in believing the false meaning. The questioner is advised to distance themselves from the whispers of disbelief and apostasy.