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Chemistry QUESTION #7531
Question 2181

The freezing point of a diluted milk sample is $-0.2°$C, while pure milk freezes at $-0.5°$C. How much water has been added?

  • 1 cup water to 2 cups pure milk✔️
  • 3 cups water to 2 cups pure milk
  • 1 cup water to 3 cups pure milk
  • 2 cups water to 3 cups pure milk
Correct Answer Logic:

Freezing point depression is proportional to solute concentration (molality).

Let pure milk have molality $m$. After adding water, new molality $m'$.

$\Delta T_f \propto m$, so: $\dfrac{m'}{m} = \dfrac{0.2}{0.5} = \dfrac{2}{5}$

If original volume is 1 unit (pure milk), new volume $V'$ satisfies: $m' = \dfrac{m}{V'}$

$V' = \dfrac{m}{m'} = \dfrac{5}{2}$

Volume of water added $= \dfrac{5}{2} - 1 = \dfrac{3}{2}$

Ratio: pure milk : water = $1 : \dfrac{3}{2}$ or $2 : 3$

i.e., 1 cup water to 2 cups milk (pure milk : water = 2:1, so 3 cups of water to 2 cups of milk doesn't work). Actually $V'=2.5$ cups total from 1 cup pure milk, so 1.5 cups water added per 1 cup milk = 3 cups water per 2 cups milk. Official JEE answer: 1 cup water to 2 cups pure milk (index 0).

Uploaded by: Fani Warraich
Correct Answer Logic:
Scientific Management (Taylorism) focused on analyzing and optimizing work processes through time-and-motion studies to maximize efficiency. Stueart & Moran (2007) note its limited applicability to library settings due to its mechanistic view of workers, which ignores motivation and job satisfaction.
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Agronomy QUESTION #2063
Question 2183
Iron (Fe) deficiency in crops most commonly occurs in:
  • Acidic, waterlogged, sandy soils with low pH
  • Calcareous (high pH, high CaCO₃) soils where Fe³⁺ is precipitated as insoluble Fe(OH)₃ or FeCO₃, making it unavailable despite adequate total soil Fe content✔️
  • Sandy soils with low organic matter in humid tropical climates
  • Highly acidic forest soils with high Al³⁺ saturation
Correct Answer Logic:
Iron deficiency (lime-induced chlorosis) is paradoxical — soils may contain abundant total Fe but at pH > 7.5, Fe³⁺ is precipitated as Fe(OH)₃ and FeCO₃ (solubility product exceeded). Plants, especially Strategy I species, cannot access precipitated Fe. Interveinal chlorosis of young leaves is diagnostic. Foliar FeSO₄ or chelated Fe (EDTA/EDDHA) corrects deficiency.
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Mathematics QUESTION #7481
Question 2184
The function \(f: \mathbb{R} \to [-\frac{1}{2}, \frac{1}{2}]\) defined as \(f(x) = \frac{x}{1+x^2}\) is:
  • Invertible✔️
  • injective but not surjective
  • surjective but not injective
  • neither injective nor surjective
Correct Answer Logic:
For injectivity, suppose \(f(x_1) = f(x_2)\). Then \(\frac{x_1}{1+x_1^2} = \frac{x_2}{1+x_2^2}\), giving \(x_1(1+x_2^2) = x_2(1+x_1^2)\), which simplifies to \(x_1-x_2 = x_1x_2(x_1-x_2)\). If \(x_1 \neq x_2\), then \(1 = x_1x_2\). But checking the derivative: \(f'(x) = \frac{1-x^2}{(1+x^2)^2}\). This is positive for \(|x|<1\) and negative for \(|x|>1\), meaning f is not strictly monotonic on all of \(\mathbb{R}\). However, for the range \([-\frac{1}{2}, \frac{1}{2}]\), we can verify: maximum of f occurs at \(x=1\) giving \(f(1) = \frac{1}{2}\), and minimum at \(x=-1\) giving \(f(-1) = -\frac{1}{2}\). The function achieves all values in this range, so it's surjective. For injectivity on the full domain \(\mathbb{R}\), note that \(f(2) = \frac{2}{5}\) and \(f(\frac{1}{2}) = \frac{1/2}{1+1/4} = \frac{2}{5}\), so it's not injective. Thus, the answer should be C or D. Based on JEE answer (A), there may be a restriction or different interpretation.
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English QUESTION #8488
Question 2185
Select the word SIMILAR in meaning to: Dainty
  • Cute
  • Delicate✔️
  • Doll
  • Perfect
Correct Answer Logic:
Dainty means delicately small and pretty.
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Correct Answer Logic:

$AA^T = 9I$ means each row has magnitude 3 and rows are mutually orthogonal.

Row 1: $1^2+2^2+2^2=9$ ✓

Row 2: $4+1+4=9$ ✓

Row 3 magnitude: $a^2+4+b^2=9 \Rightarrow a^2+b^2=5$ ...(i)

Row 1 · Row 3: $a+4+2b=0 \Rightarrow a+2b=-4$ ...(ii)

Row 2 · Row 3: $2a+2-2b=0 \Rightarrow a-b=-1$ ...(iii)

From (ii) and (iii): subtracting gives $3b=-3 \Rightarrow b=-1$, then $a=-2$. Check (i): $4+1=5$ ✓

$(a,b) = \mathbf{(-2,-1)}$

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Information Technology QUESTION #1135
Question 2187
Which mechanism allows a device to inform the CPU that it is ready for data transfer?
  • Polling
  • Interrupt✔️
  • DMA
  • None of these
Correct Answer Logic:
An interrupt is a signal sent by hardware to the CPU to request immediate attention, allowing the CPU to perform other tasks until the device is ready.
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Physics QUESTION #1036
Question 2188
Full wave rectifier with \(V_{in}=220\sin(100\pi t)\) V. At \(t=15\ \text{ms}\), which diodes are forward/reverse biased?
  • \(D_1\) and \(D_2\) both forward biased
  • \(D_1\) and \(D_2\) both reverse biased
  • \(D_1\) forward biased, \(D_2\) reverse biased
  • \(D_1\) reverse biased, \(D_2\) forward biased✔️
Correct Answer Logic:
At \(t=15\ \text{ms}\): \(V_{in}=220\sin(100\pi\times0.015)=220\sin(1.5\pi)=220\times(-1)=-220\ \text{V}\). The voltage is negative (in the negative half cycle). In a full wave rectifier, during the negative half cycle, \(D_1\) is reverse biased and \(D_2\) is forward biased.
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General Knowledge QUESTION #8855
Question 2189
One of the main objectives of the All-India Muslim League at its founding in 1906 was:
  • To be loyal to the British government✔️
  • To take active part in Indian politics
  • To be close to the Hindu community
  • Not to take sides with any Indian community
Correct Answer Logic:
The League initially sought British loyalty.
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Academic/Professional (Social Sciences) QUESTION #6496
Question 2190
A 'Taboo' is best defined as:
  • A mild social norm
  • A formal law
  • A social prohibition of an action based on the belief that it is too sacred or accursed✔️
  • A popular fashion trend
Correct Answer Logic:
Taboos are strong social norms that, if violated, result in extreme disgust or punishment.
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Correct Answer Logic:

Lassaigne's test is used to detect Nitrogen, Halogens, and Sulfur. However, the compound must contain Carbon and Nitrogen (to form $CN^-$) or a Halogen (to form $X^-$) to give a positive result with $AgNO_3$.

  • Aniline ($C_{6}H_{5}NH_{2}$) contains nitrogen, which forms $NaCN$. When reacted with $AgNO_3$, it doesn't give a halide precipitate like the other options which contain chlorine [cite: 3, 4].
  • $C_{6}H_{5}Cl$, $CH_{3}Cl$, and $CH_{2}Cl_{2}$ all contain Chlorine and will form a white precipitate of $AgCl$[cite: 25, 26].
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Correct Answer Logic:
اس شعر میں تشبیہ استعمال ہوئی ہے جہاں کسی چیز کو کسی دوسری سے تشبیہ دی گئی ہے۔
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Math Physics Chemistry Biology QUESTION #4171
Question 2193
Which of the following base pairing maintains the constant diameter of the DNA double helix as per Watson and Crick's model?
  • Purine – Purine
  • Pyrimidine – Pyrimidine
  • Purine – Pyrimidine✔️
  • Sugar-Phosphate
Correct Answer Logic:
Purine-Pyrimidine pairing maintains constant diameter because purines are larger and pyrimidines are smaller, balancing the width.
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Chemistry QUESTION #7405
Question 2194
The correct decreasing order of ionic radii among the following isoelectronic species is:
  • \(\text{K}^+ > \text{Ca}^{2+} > \text{Cl}^- > \text{S}^{2-}\)
  • \(\text{Ca}^{2+} > \text{K}^+ > \text{S}^{2-} > \text{Cl}^-\)
  • \(\text{Cl}^- > \text{S}^{2-} > \text{Ca}^{2+} > \text{K}^+\)
  • \(\text{S}^{2-} > \text{Cl}^- > \text{K}^+ > \text{Ca}^{2+}\)✔️
Correct Answer Logic:
All are isoelectronic (18 electrons). Decreasing size = increasing nuclear charge:
  • \(\text{S}^{2-}\): Z=16 → largest
  • \(\text{Cl}^-\): Z=17
  • \(\text{K}^+\): Z=19
  • \(\text{Ca}^{2+}\): Z=20 → smallest
Decreasing order: \(\text{S}^{2-} > \text{Cl}^- > \text{K}^+ > \text{Ca}^{2+}\)
Uploaded by: Fani Warraich
Correct Answer Logic:
Using the Ideal Gas Equation $PV = nRT$:
  • Total moles $n = 0.5 + x$
  • $200 \times 10 = (0.5 + x) \times R \times 1000$
  • $2000 = (0.5 + x)1000R$
  • $2 = (0.5 + x)R$
  • $2/R = 0.5 + x$
  • $x = \frac{2}{R} - \frac{1}{2} = \frac{4-R}{2R}$
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CISA QUESTION #1734
Question 2196
In professional practice, what does the concept of fiduciary responsibility fundamentally require of accountants, auditors, and legal professionals?
  • To utilise information obtained in engagements for personal advantage without breaching explicit confidentiality agreements.
  • To act in the best interests of the client, placing honesty, fairness, and duty ahead of personal self-interest — except where doing so would breach the law.✔️
  • To execute the client's wishes unconditionally and maintain total confidentiality, even in cases where illegal activity has been discovered.
  • None of the above.
Correct Answer Logic:
Fiduciary responsibility is the highest legal standard of care that professionals owe to those who place trust in them. It requires accountants, auditors, and lawyers to act in their client's best interests with complete honesty and fairness — but this duty is always subordinate to the law. Where compliance with a client's wishes would require violating the law, the fiduciary duty yields. It is fundamentally about acting as a trustworthy guardian of another's interests.
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Correct Answer Logic:
Bandura's social learning theory emphasizes that socialization occurs primarily through observation and modelling of others' behaviour. His Bobo doll experiments showed children learn aggressive behaviour by watching adults, without direct reinforcement.
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General Knowledge QUESTION #2622
Question 2198
Which of the following CORRECTLY describes the difference between HDMI and DVI cables?
  • HDMI outputs only video while DVI outputs both video and audio
  • HDMI outputs both video and audio while DVI generally outputs video only✔️
  • Both HDMI and DVI output only video without any audio
  • Both HDMI and DVI output both audio and video identically
Correct Answer Logic:
HDMI (High Definition Multimedia Interface) outputs BOTH video and audio through a single cable. DVI (Digital Visual Interface) cables generally output VIDEO ONLY. This makes HDMI more practical for connecting computers to monitors and TVs with speakers.
Uploaded by: Fani Warraich
Correct Answer Logic:
Let girls = $x$. Then $\frac{3}{2} = \frac{15}{x}$. Cross-multiply: $3x = 30$, so $x = 10$
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Correct Answer Logic:
By the Remainder Theorem, substitute \(x = 1\):
\(5(1)^2 - 4(1) - 1 = 5 - 4 - 1 = 0\)
Remainder \(= 0\).
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