Explanation

Usually in is used after trust or "believe".

We trust in one God

means ہم ایک خدا پر یقین رکھتے ہیں

so the option "in" is best to keep the meaning of the original sentence.

Explanation

We generally use in after harm.

No harm in + ing form of a verb کوئی حرج نہیں

There is no harm In meeting him.

اس سے ملنے میں کوئی حرج نہیں۔

Explanation

"My aunt will visit my home."

"میری خالہ میرے گھر آئیں گی۔"

"Visit" is the correct verb form to use with "will" because "will" is followed by the base form of the verb to indicate future tense.

Explanation

We generally use with after filled. 

With is a preposition here.

Her eyes were filled with tears اس کی آنکھیں آنسوؤں سے بھر گئیں۔

Explanation

Effective means something that works well or produces the desired result.

Here, the sentence means the medicines successfully cure cold, so “effective” is the best fit.