Question Discussion & Solution

The correct answer is 7.

Key Points

• The pH value of salts of strong acid and strong base is 7.
  • The salts are from a strong acid and strong base do not hydrolyze and the resulting salt pH will remain 7.
  • The anion in the salt form's strong base does not attract the H+ from the water.

Additional Information

• Salt of a strong acid and a weak base is acidic with a pH value less than 7 because acid is strong which retains the pH value less than 7.
• Salt of a weak acid and strong base is basic with a pH value of more than 7 because the base is strong hence pH of the whole solution will be more than 7.
• Salt of a strong acid and strong base is neutral because both are strong and cancels strong effects of each other, the pH will be 7.

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 is as follows:

The first letter in each group is a series of vowels in reverse alphabetical order.

The second letter in each group is the opposite letter to the first one.

Hence, “AZ” is the correct answer.

The correct answer is Violence.

Key Points

• Violence
  • It is defined by the World Health Organization in the WRVH as “the intentional use of physical force or power, threatened or actual, against oneself, another person, or against a group or community, that either results in or has a high likelihood of resulting in injury, death, psychological harm, maldevelopment or deprivation” 

Additional Information

• Nonviolence
  • It is the personal practice of not causing harm to one's self and others under every condition.
• Hatred
  • It is an angry or resentful emotional response to certain people or ideas. 

Given,

Given Expression: 70S7P21R2Q15

According to question :

=70 ÷ 7 + 21 × 2 – 15

Using BODMAS rule,

=10 + 21 × 2 – 15

= 10 + 42 – 15

= 52 – 15

= 37

Hence, value of the given expression is ‘37’.