Which of the following pairs of products obtained from petroleum distillation and their uses are correctly matched? 1. Petroleum ether : Used as solvent 2. Petroleum jelly : Used to make coating of metals 3. Petroleum wax : Used as rubber solvent 4. White spirit : Used for making candles Select the answer using the code given below.
- A.1, 3 and 4
- B.1 and 2
- C.2, 3 and 4
- D.3 and 4 only
Correct answer
Explanation
The correct answer is B, 1 and 2. Petroleum ether is a solvent and petroleum jelly is spread on metal surfaces as a protective coating, while the uses given for petroleum wax and white spirit have been swapped around.
Fractional distillation of crude oil separates it by boiling range. Petroleum ether, a very light fraction, dissolves fats, oils and resins, so it is used as a laboratory and industrial solvent. Petroleum jelly (vaseline) is a soft semi-solid used in ointments and as a greasy coating that keeps metal parts from rusting. Petroleum (paraffin) wax is the solid used to make candles, wax paper and polish, and white spirit is a solvent and paint thinner.
A is wrong because pair 3 and pair 4 are mismatched. C is wrong for the same reason, although pair 2 is right. D is wrong because pairs 3 and 4 are exactly the two incorrect pairs.
Exam tip: paraffin wax = candles; white spirit = paint thinner; petroleum ether = solvent; petroleum jelly = ointment and rust coating.
Practice Questions
View allConsider the following pairs : (Commonly used / consumed materials : Unwanted or controversial chemicals likely to be found in them) 1. Lipstick : Lead 2. Soft drinks : Brominated vegetable oils 3. Chinese fast food : Monosodium glutamate Which of the pairs given above is/are correctly matched ?
- A.1 only
- B.2 and 3 only
- C.1 and 3 only
- D.1, 2 and 3
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Each product has been linked to the chemical paired with it. Lead has been found as a trace contaminant in many lipsticks, coming from colour pigments; since lipstick is swallowed in small amounts, regular use raises concern because lead is a toxic heavy metal that harms the nervous system.
Read the full explanation →Which 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.
Show answer
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
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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.
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