Safety Blank 1 Question 3[select: , Dichloromethane, Water, Sodium hydrogen carbonate, Paracetemol, Startch] is a possible carcinogen that should be handled in the fume cupboard. When shaking the separating funnel, the tip should be facing Blank 2 Question 3[select: , towards the back of the fume cupboard, at your lab coat, at the floor, at someone's face] .多重下拉选择题
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Question

Safety Blank 1 Question 3[select: , Dichloromethane, Water, Sodium hydrogen carbonate, Paracetemol, Startch] is a possible carcinogen that should be handled in the fume cupboard. When shaking the separating funnel, the tip should be facing Blank 2 Question 3[select: , towards the back of the fume cupboard, at your lab coat, at the floor, at someone's face] .多重下拉选择题

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BlackTom AI · Accepted Answer

Dichloromethane is a volatile chlorinated solvent with documented health hazards, so it is the chemical from the list that should be handled inside a fume cupboard. Relevant knowledge points: dichloromethane (also called methylene chloride) is volatile, gives off vapour that can be inhaled, and is classified as a possible carcinogen; a fume cupboard prevents inhalation exposure by removing vapours. The other substances listed (water, sodium hydrogen carbonate, paracetamol, starch) are not volatile carcinogenic solvents and do not require fume-cupboard handling for vapour control.

Step-by-step reasoning:
1. Examine each option for the first blank: water is non-toxic and non-volatile in this context; sodium hydrogen carbonate and starch are solids with low volatility; paracetamol (acetaminophen) is a pharmaceutical solid, not a volatile solvent. Dichloromethane is a common organic solvent known for volatility and carcinogenic risk. Therefore the correct choice is dichloromethane.
2. For the second blank consider safe technique when shaking a separating funnel: you must vent the funnel (open the stopcock briefly) to release built-up pressure, and you must point the tip (the outlet and any spray if the stopcock blows) away from people and upward into the safe zone of the fume hood. The safest orientation is towards the back of the fume cupboard where vapours and any accidental spray are contained and directed away from the user.
3. Evaluate incorrect second-blank options: pointing at your lab coat risks soaking clothing and skin exposure; pointing at the floor can splash others or create trip hazards and does not direct vapour into the hood’s airflow; pointing at someone’s face is obviously dangerous.

Why the answers are correct: Dichloromethane requires fume-cupboard handling because of its vapour hazard and carcinogenic potential. When agitating a separating funnel, directing the tip towards the back of the fume cupboard ensures any liquid or vapour released is contained and moves away from personnel.