The Poisonous nature of Carbon monoxide (CO) is due to its
- A.insolubility in water
- B.ability to form a complex with haemoglobin
- C.ability to reduce some metal oxides
- D.property of having one sigma bond
Correct answer
Explanation
The correct answer is B, ability to form a complex with haemoglobin. Carbon monoxide binds to the haemoglobin of red blood cells to form carboxyhaemoglobin, so the blood can no longer carry oxygen to the tissues.
Haemoglobin holds carbon monoxide about 200 times more strongly than it holds oxygen, and the complex breaks up very slowly. Even a small amount of CO in the air therefore cuts the oxygen supply to the brain and heart, causing headache, dizziness, unconsciousness and death. CO has no colour or smell, which makes it more dangerous. It forms when fuel burns in too little air, as in a closed room with a coal stove or in vehicle exhaust.
A is wrong because solubility in water has nothing to do with how CO harms the body.
C is wrong because CO reducing metal oxides is why it is used in metallurgy, as in a blast furnace; it is not the cause of its toxicity.
D is wrong because CO actually has a triple bond, one sigma and two pi bonds, and bond type is not why it is poisonous.
Exam tip: CO + haemoglobin → carboxyhaemoglobin; affinity about 200 times that of oxygen; colourless and odourless.
Practice Questions
View allWhich one of the following is not true for anodizing process?
- A.It makes aluminium corrosion resistant.
- B.Metals like aluminium, titanium and magnesium can be anodized.
- C.Clean aluminium article is the anode and oxygen gas is evolved at the cathode.
- D.It is used in aircraft industry.
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In anodizing the clean aluminium article is indeed the anode, but oxygen is released at the anode, not at the cathode; hydrogen is released at the cathode.
Read the full explanation →Which one of the following statements is not correct?
- A.The response of the ear to sound of increasing intensity is approximately logarithmic.
- B.The sensitivity of the human ear does not vary with the frequency of the sound.
- C.When two or more waves traverse the same medium, the displacement of any element of the medium is the algebraic sum of the displacements due to each wave.
- D.Longitudinal waves can travel in all media—solids, liquids and gases.
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The statement that the sensitivity of the human ear does not vary with frequency is false, because the ear is far more sensitive to some frequencies than to others.
Read the full explanation →Kwashiorkor disease in children is caused by
- A.sufficient carbohydrates but less fats in diet
- B.sufficient carbohydrates and fats but deficient proteins in diet
- C.sufficient vitamins but deficient fats in diet
- D.sufficient fats but deficient vitamins in diet
Show answer
Kwashiorkor is a disease of protein deficiency in a child who still gets enough calories. It usually appears when a child is weaned from breast milk onto a starchy diet with little protein.
Read the full explanation →Which one of the following is the correct order of pH for the given substances?
- A.Coffee < Lemon juice < Milk of magnesia < Blood
- B.Milk of magnesia < Blood < Coffee < Lemon juice
- C.Lemon juice < Blood < Coffee < Milk of magnesia
- D.Lemon juice < Coffee < Blood < Milk of magnesia
Show answer
Arranged from most acidic to most basic, the four substances fall in exactly this order. Lemon juice, rich in citric acid, has a pH of about 2 to 2.5.
Read the full explanation →Which one of the following diseases may be caused by the deficiency of vitamin C?
- A.Rickets
- B.Rabies
- C.Hepatitis
- D.Scurvy
Show answer
Scurvy is caused by a lack of vitamin C, or ascorbic acid, which the body needs to make collagen, the protein that holds skin, gums and blood vessels together.
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