1. In a language with zero-based indexing, at what index will the 100th item in an array

 In a language with zero-based indexing, the index of the 100th item in an array will be 99. This is because the first item in the array is at index 0, so you count up from there: the second item is at index 1, the third item is at index 2, and so on. To get the index of the 100th item, you subtract 1 from 100, which gives you 99.

Extra: Zero-based indexing is a way of numbering where the first element of a sequence is assigned the index 0 rather than 1. Many programming languages, such as C, C++, Java, Python, and JavaScript, use zero-based indexing for arrays, lists, and other ordered data structures.

One reason for this convention is that the index can be seen as an offset from the start of the array. For example, the first element is zero steps away from the start of the array, the second element is one step away, and so on. This system can make certain operations, like iterating over the array or calculating the position of an element, simpler and more efficient in terms of processor instructions.