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The correct answer is Photochemical smog.

Key Points

• The term 'Brown Air' refers to photochemical smog, which is a type of air pollution resulting from the reaction of sunlight with pollutants like nitrogen oxides (NOx) and volatile organic compounds (VOCs).
• It primarily occurs in urban areas with high vehicle emissions and industrial activity, especially in warm and sunny conditions.
• Photochemical smog contains harmful pollutants such as ozone (O3), peroxyacetyl nitrate (PAN), and aldehydes, which can cause respiratory and cardiovascular issues.
• The brownish color of the air is due to nitrogen dioxide (NO2), a major component of photochemical smog.
• Regions like Los Angeles, Mexico City, and Delhi are frequently affected by photochemical smog due to their dense population and high emissions.

Additional Information

• Industrial smog:
• Also known as "gray smog," it forms in cooler, humid conditions and primarily consists of sulfur dioxide (SO2) and particulate matter.
• This type of smog is typically associated with the burning of fossil fuels like coal and oil, which release sulfur compounds.
• It was famously observed during the London Smog of 1952, which caused severe health and environmental impacts.
• Sulphurous smog:
• This is another name for industrial smog, as it primarily contains sulfur dioxide and other sulfur compounds.
• It leads to acid rain and contributes to respiratory problems and environmental degradation.
• Acid fumes:
• Acid fumes result from the emission of acidic gases like sulfur dioxide (SO2) and nitrogen oxides (NOx) into the atmosphere.
• These gases react with water vapor to form acidic substances such as sulfuric acid (H2SO4) and nitric acid (HNO3), which contribute to acid rain.
• While acid fumes are related to air pollution, they are not the same as photochemical smog.
• Main Theme:
• Photochemical smog is a significant environmental issue caused by human activities like industrialization and vehicular emissions.
• Efforts to control smog include reducing emissions of NOx and VOCs, promoting the use of cleaner fuels, and adopting stricter environmental regulations.

According to the question, the first three letters of English alphabet are reversed and so on... and the last two letters are reversed:

ABC  DEF  GHI  JKL  MNO  PQR  STU  VWX  YZ  →  CBA  FED  IHG  LKJ  ONM  RQP  UTS  XWV  ZY

So, 19^th letter to the right of 17^th letter to the left of 5^th letter from right → CBAFEDIHGLKJONMRQPUTSXWVZY → V

Hence, 'Option 1' is the correct answer.

The correct answer is zero.

Key Points

• The gravitational force inside the Earth decreases with depth because it depends on the mass enclosed within the radius of the point considered.
• At the center of the Earth, the effective gravitational force becomes zero as the mass is symmetrically distributed around the center.
• The weight of a body is given by the formula W = mg, where g (gravitational acceleration) becomes zero at the Earth's center, leading to a weight of zero.
• This is supported by Newton's law of gravitation and the shell theorem, which states that the net gravitational force inside a uniform spherical shell is zero.
• The concept is theoretical, as the Earth's core is inaccessible, but it is well-established in physics based on mathematical models and fundamental laws.

Additional Information

• Option 2: Twice the weight at the Earth's surface
• This option is incorrect because the gravitational force does not increase inside the Earth. Instead, it decreases with depth.
• The concept of gravitational force doubling is not supported by scientific theories or mathematical models.
• Option 3: Half the weight at the Earth's surface
• This option is also incorrect. While the gravitational force decreases with depth, it does not become exactly half at any specific layer inside the Earth.
• The weight decreases gradually and reaches zero at the center due to the uniform distribution of mass around the center.
• Option 4: Infinite
• This option is incorrect as the gravitational force cannot become infinite at the Earth's center. Instead, it becomes zero as per the shell theorem and Newtonian physics.
• The concept of infinite weight contradicts established scientific principles.
• Related Concept: Gravitational Force and Weight
• Gravitational force is the attractive force between two masses, governed by Newton's law of gravitation.
• The weight of a body is the force exerted by gravity on the mass of the body.
• Inside the Earth, the gravitational force decreases linearly with depth until it becomes zero at the center.

Given:

Total mixture = 729 ml

Milk : Water = 7 : 2

We need to add water to make the new ratio Milk : Water = 7 : 3

Formula used:

Total milk = \(\dfrac{7}{9}\) of total mixture

Total water = \(\dfrac{2}{9}\) of total mixture

New water amount = \(\dfrac{1}{3}\) of total mixture

Additional water to be added = New water - Initial water

Calculation:

Total milk = \(\dfrac{7}{9} \times 729 = 567 , \text{ml}\)

Total water = \(\dfrac{2}{9} \times 729 = 162 , \text{ml}\)

Let the additional water added be x. Then,

⇒ Milk : Water = \(\dfrac{567}{162 + x} = \dfrac{7}{3}\)

⇒ \(\dfrac{567}{162 + x} = \dfrac{7}{3}\)

⇒ \(3 \times 567 = 7 \times (162 + x)\)

⇒ \(1701 = 1134 + 7x\)

⇒ \(1701 - 1134 = 7x\)

⇒ \(567 = 7x\)

⇒ \(x = \dfrac{567}{7} = 81 , \text{ml}\)

∴ The correct answer is option (4).

The logic followed is:

ABCD: WXYZ

Similarly,

EFGH: ?

Hence, the correct answer is "Option 3".

Given:

Four consecutive even numbers A, B, C, D

Average of A, B, C, D = 99

Find product of B and D

Formula used:

Average = (Sum of numbers) / 4

Calculations:

Consecutive even numbers: A, A + 2, A + 4, A + 6

Average = (A + (A + 2) + (A + 4) + (A + 6)) / 4 = 99

⇒ (4A + 12) / 4 = 99

⇒ 4A + 12 = 396

⇒ 4A = 384

⇒ A = 96

B = A + 2 = 98, D = A + 6 = 102

Product of B and D = 98 × 102 = 9996

Answer: 9996

The logic followed here is:

​6 : 5 → (6 ÷ 2) + 2 = 3 + 2 ⇒ 5

Similarly, 

8 : ? → (8 ÷ 2) + 2 = 4 + 2 ⇒ 6

Hence, "Option 1" is the correct answer.

Alternate Method ​6 : 5 

→ (2 × 3) ⇒ 6

→ (2 + 3) ⇒ 5

Similarly, 

8 : ?

→ (2 × 4) ⇒ 8

→ (2 + 4) ⇒ 6

Given:

Father's age = Son's age + 30 years

After 10 years, Father's age = 3 × Son's age

Calculation:

Let Son's current age = x

Father's current age = x + 30

After 10 years:

(x + 30 + 10) = 3 × (x + 10)

(x + 40) = 3 × (x + 10)

⇒ x + 40 = 3x + 30

⇒ 40 - 30 = 3x - x

⇒ 10 = 2x

⇒ x = 10 ÷ 2 = 5

∴ Son's current age is 5 years, and the correct answer is option (1).

The correct answer is Chowdhury Rehmat Ali.

Key Points

• Chowdhury Rehmat Ali is credited with coining the name "Pakistan" in 1933, through his pamphlet titled "Now or Never: Are We to Live or Perish Forever?".
• The name "Pakistan" is derived from a combination of letters representing different regions, specifically Punjab, Afghania (North-West Frontier Province), Kashmir, Sindh, and Baluchistan.
• Rehmat Ali was a student at Cambridge University in England when he proposed the idea of creating a separate state for Muslims in the Indian subcontinent.
• The name "Pakistan" symbolizes "the land of the pure," derived from the Persian and Urdu words "Pak" (pure) and "Stan" (place).
• His idea laid the foundation for the later political movement advocating for the creation of Pakistan, led by Muhammad Ali Jinnah and the All-India Muslim League.

Additional Information

• Liaquat Ali Khan:
• He was the first Prime Minister of Pakistan after its independence in 1947.
• Liaquat Ali Khan played a significant role in the political development of Pakistan and is considered one of its founding fathers.
• He was a close associate of Muhammad Ali Jinnah and contributed to the constitutional and administrative groundwork of the country.
• Mohammad Ali Jinnah:
• He is known as the "Father of the Nation" in Pakistan for his pivotal role in the creation of the country.
• Jinnah led the All-India Muslim League and successfully advocated for the partition of British India, which resulted in the establishment of Pakistan in 1947.
• Although Jinnah did not coin the name "Pakistan," he embraced the concept and worked tirelessly to realize the vision proposed by Chowdhury Rehmat Ali.
• Fazlul Haque:
• Fazlul Haque was a prominent Bengali politician and the Chief Minister of Bengal.
• He is known for presenting the Lahore Resolution in 1940, which called for independent states for Muslims in the northwestern and eastern zones of India.
• The Lahore Resolution was a significant milestone in the struggle for Pakistan, but Fazlul Haque was not involved in coining the name "Pakistan."
• Main Theme:
• The idea of Pakistan originated from the demand for a separate nation for Muslims in the Indian subcontinent, stemming from cultural, religious, and political differences.
• While Chowdhury Rehmat Ali coined the name, the movement gained momentum under the leadership of Muhammad Ali Jinnah and culminated in the creation of Pakistan on August 14, 1947.
• The term "Pakistan" reflects the regions it aimed to incorporate and symbolizes purity, as envisioned by its proponents.

The logic followed here is :-

From the given two different cubes the adjacent sides are as shown below :

As 5 dots is common on both the dices, it is clear that 2 Dots, 4 Dots, 1 Dot and 3 Dots are adjacent to it, and the remaining i.e. 6 Dots will be opposite to it.

Opposite pairs:

4 Dots → 3 Dots

2 Dots → 1 Dot

5 Dots → 6 Dots

So, the opposite side of "4 Dots" will be side "3 Dots".

Hence, the correct answer is "Option 1".