The following are multiple choice questions (with answers) about medical knowledge.   **Question:** Which of the following is used as, surface hardener in Impression material?   (A) 2% potassium sulfate   (B) 0.2% potassium sulfate   (C) 2% sodium sulfate   (D) 4% potassium sulfate
['(A) 2% potassium sulfate <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) 2% potassium sulfate \n (B) 0.2% potassium sulfate \n (C) 2% sodium sulfate \n (D) 4% potassium sulfate <> possible answers', '  Which of the following is used as, surface hardener in Impression material? <> context@']