How can a questioner atone for the oaths he broke in his repeated attempts to quit smoking, and what is the effective way to get rid of this habit, and can smoking be a reason for his supplications not being answered?

If the three oaths were sworn at the same time and with the intention of emphasis, then you owe a single expiation. However, if they were sworn at different times, then you owe an expiation for each oath. The expiation for an oath is that mentioned in the noble verse: "Allah will not impose blame upon you for what is unintentional in your oaths..."

The questioner is advised to cease frequent oath-taking and to abandon the bad habit (smoking) with strong resolve and patience. What aids in this is sincerity of intention for Allah, genuine desire, abundant supplication, seeking assistance from righteous friends, and avoiding those who practice this habit. Smoking may be an impediment to the दुआ (supplication) being answered, due to the Prophet's (peace and blessings be upon him) saying: "O Sa'd: Make your food pure, and your supplication will be answered."