Correct spelling, explanation: the choice between into and in to depends on the context in which the words are used. Into is used when you’re indicating movement or a change of state from one place, condition, or situation to another. In to, on the other hand, is used when in is part of the verb phrase and to is a preposition. To determine which form is correct, consider the grammatical function of in and to in the sentence. If they are functioning separately as a preposition and an infinitive particle, respectively, use into. If they are part of a verb phrase, use in to.

Definition of into::
1). preposition, to the inside or middle of a place, container, area, etc.
She walked into the room.
She carefully stepped into the old bookstore, eager to explore the shelves lined with dusty volumes.
2. preposition, used to show when a person or thing is changing from one form or condition to another
The magician turned a hat into a rabbit right before our eyes.
She poured the ingredients into the mixing bowl to start baking the cake.

Collocations with into:
Some most commonly used collocations include:
1. Dive into: to enthusiastically engage in or start something with great energy.
She dove into her new job, eager to learn and contribute.
2. Transform into: to change or convert something from one form or state to another.
The caterpillar transformed into a beautiful butterfly.
3. Look into: to investigate, examine, or research something.
The team will look into the issue and provide a solution.
4. Turn into: similar to transform into, it refers to the process of changing something from one state or condition to another.
The rainy day turned into a sunny afternoon.

Correct spelling, explanation: the difference between into and in to lies in their usage and grammatical functions. The choice between into and in to depends on the grammatical structure of the sentence and the specific meaning you want to convey. In many cases, into is used to indicate movement or a change of state, while in to is used when in and to have separate grammatical functions. It’s important to understand the context and the intended meaning to use the correct form.