Which of the following substances can be irritating to the lungs if you inhale the fumes?

• A. Water vapor (H_2O)
• B. Sodium chloride (NaCl)
• C. Glucose (C_6H_{12}O_6)
• D. Ammonia (NH_3)

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the nature of each substance listed. Water vapor (H\_2O) is simply the gaseous form of water and is generally not harmful when inhaled in normal amounts.
2. Step 2: Sodium chloride (NaCl) is common table salt, which is a solid at room temperature and does not produce fumes under normal conditions, so it is unlikely to irritate the lungs by inhalation.
3. Step 3: Glucose (C\_6H\_{12}O\_6) is a solid sugar molecule and does not readily vaporize or produce fumes that can be inhaled, so it is not typically irritating to the lungs.
4. Step 4: Ammonia (NH\_3), however, is a gas at room temperature and is known to be a respiratory irritant. Its fumes can cause irritation to the mucous membranes and lungs upon inhalation.
5. Step 5: Therefore, among the substances listed, ammonia (NH\_3) is the one that can be irritating to the lungs if its fumes are inhaled.