Question Discussion & Solution

The Correct Answer is Option 4 i.e Propane.

• Methane:
  • Methane is a colorless odorless gas. 
  • It is also known as marsh gas or methyl hydride. 
  • The molecular formula is CH₄.
• Pentane:
  • Pentane is found in alcoholic beverages. 
  • Pentane is present in hop oil. 
  • Pentane is any or one of the organic compounds with the formula C₅H₁₂. 
  • Its properties are very similar to those of butane and hexane.
• Propane:
  • Propane, sometimes known as liquefied petroleum gas, or LPG.
  • Propane is a three-carbon alkane gas (C₃H₈).
  • Propane is produced as a by-product of natural gas processing and crude oil refining. 
• Butane:
  • Butane is a colorless gas with a faint petroleum-like odor.
  • It is shipped as a liquefied gas under its vapor pressure. 
  • Butane is a straight-chain alkane composed of 4 carbon atoms. 
  • C₄H₁₀ is the molecular formula of butane.

Here the pattern is,

Hence, B9 is the correct answer.

The correct answer is Soap solution is alkaline.

Concept:

• Indicators are the substances that are used to identify whether the given substance is an acid or a base.
• There are two types of indicators:
  • Natural: These indicators are obtained from natural sources like plants. 
  • Turmeric, litmus, china rose petals, etc., are some of the naturally occurring indicators.
  • The most commonly used natural indicator is litmus.
  • It is extracted from lichens.
  • It is available in the form of a solution, or in the form of strips of paper, known as litmus paper.
  • Generally, it is available as red and blue litmus paper.
  • Man-made: Phenolphthalein, Methyl orange are some of the man-made indicators.

Explanation:

• • The indicators change their colour when added to a solution containing an acidic or a basic substance.
  • Turmeric is a natural indicator. It contains the substance

curcumin which changes colour with pH.

• When a substance is basic, the colour is red, whereas when the substance is acidic, the colour of turmeric turns yellow to brown

• Turmeric stains on the shirt turn red when washed with soap because the soap solution is basic in nature which changes the yellow colour of Turmeric into red colour.
• It is because turmeric contains tartaric acid, while the soap contains a sodium hydroxide base. When an acid reacts with a base, a neutralization reaction takes place and the stain becomes neutral.

Neutralization Reaction

• A neutralization reaction can be defined as a chemical reaction in which an acid and base quantitatively react together to form salt and water as products.

Saponification

• Saponification is the hydrolysis of an ester with NaOH or KOH to give alcohol and sodium or potassium salt of the acid.

The pattern followed here is:

This is an alternate series of subtraction. The first number is subtracted by 2 to get the second number and then 4 is subtracted from the second number to get the third number and so on.

Hence, 42 is the correct answer.

Number of persons between two different persons = Total number of persons – (position of person from left + position of persons from right)

Sum of positions of K & T from opposite ends = 23 + 28 = 51, i.e. less than the total number of students (<60)

Therefore, number of students between K & T = Total number of students - (position of K from left + position of T from right)

60 – (23 + 28) = 60 – 51 = 9