I will be carrying my personal laptop to New Delhi from USA in a laptop bag. I am planning to keep a new iPad (cost $900) in my laptop bag. If I keep it unpacked and keep the box in the checked in bag, would it be counted as a second laptop or computer which violates customs law? Please let me know if I should go ahead an declare it?
Please note that what you are doing is illegal, as you are effectively importing goods in the country, trying to pass them as personal items which you had on you when you left the USA. This is clearly not the case as you said you bought the item in India and are bringing it in with you in the USA. Moreover, the fact that you put the box in the suitcase does not render this procedure less illegal. Although many people often use such methods, these people are all violating custom laws.
Travelling with an iPad and a Laptop
Having said this, in a normal, legal situation in which you complete a return journey with the same number of devices classified for personal use, it would be uncommon for you to be stopped at customs for having both a laptop and an iPad. Questions tend to arise when you carry two similar items. For example two laptops would raise questions.
You can read more about the legal implications here and here is a similar question about iPad and laptop combination.