Is this sentence correct Open envelopes and then reseal it.?

No, the sentence "Open envelopes and then reseal it" is not grammatically correct.

Here's why:

* Pronoun Agreement: The pronoun "it" refers to the envelope, but the sentence starts with "envelopes" (plural). This creates a subject-verb agreement error.

* Ambiguity: It's not clear if the sentence is referring to one specific envelope or all of them.

Here are some ways to correct the sentence:

* Specific Envelope: "Open the envelope and then reseal it."

* Multiple Envelopes: "Open the envelopes and then reseal them."

* General Instruction: "Open the envelope and reseal it afterwards."

Choose the option that best fits the intended meaning.