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Study questions platform-wide or filter by specific tests with correct answers revealed.
Correct Answer Logic:
Since \(\vec{u}\) is coplanar with \(\vec{a}\) and \(\vec{b}\), we can write \(\vec{u} = x\vec{a} + y\vec{b} = x(2\hat{i}+3\hat{j}-\hat{k}) + y(\hat{j}+\hat{k}) = 2x\hat{i} + (3x+y)\hat{j} + (-x+y)\hat{k}\). Condition \(\vec{u} \perp \vec{a}\): \(\vec{u} \cdot \vec{a} = 2x(2) + (3x+y)(3) + (-x+y)(-1) = 0\), giving \(4x + 9x + 3y + x - y = 0\), so \(14x + 2y = 0\), thus \(y = -7x\). Condition \(\vec{u} \cdot \vec{b} = 24\): \((3x+y)(1) + (-x+y)(1) = 24\), giving \(3x+y-x+y = 24\), so \(2x+2y = 24\), thus \(x+y = 12\). From \(y=-7x\): \(x-7x = 12\), so \(-6x=12\) and \(x=-2\), giving \(y=14\). Thus \(\vec{u} = -4\hat{i} + 8\hat{j} + 16\hat{k}\), and \(|\vec{u}|^2 = 16 + 64 + 256 = 336\).
Uploaded by: Fani Warraich
General Knowledge
QUESTION #2593
Question 3162
In the decimal (base-10) number system, how many unique digit symbols are available for use?
Correct Answer Logic:
In the decimal system, there are 10 possible numbers you can use ranging from zero to nine (0, 1, 2, 3, 4, 5, 6, 7, 8, 9). This is why it is called 'base-10' — it has a base of ten distinct symbols.
Uploaded by: Fani Warraich
Math Physics Chemistry Biology
QUESTION #739
Question 3163
The range of visible wavelength spectrum is:
Correct Answer Logic:
The visible light spectrum ranges from approximately 400 nm (violet) to 750 nm (red).
Uploaded by: Fani Warraich
Urdu
QUESTION #5249
Question 3164
'اس آباد خرابے میں' کس کی خود نوشت ہے؟
Correct Answer Logic:
اس آباد خرابے میں عبدالمجید سالک کی خود نوشت سوانح عمری ہے۔
Uploaded by: Fani Warraich
Paper-I (Anatomy/Physiology and Biochemistry/Microbiology)
QUESTION #3211
Question 3165
'Negative Feedback' mechanism is used by the body to:
Correct Answer Logic:
Most hormones are regulated by negative feedback to maintain homeostasis.
Uploaded by: Fani Warraich
Boilers Mechanical Engineering
QUESTION #2444
Question 3166
The transmissibility (TR) in vibration isolation represents:
Correct Answer Logic:
Transmissibility: \(TR=F_{transmitted}/F_0=\sqrt{\frac{1+(2\zeta r)^2}{(1-r^2)^2+(2\zeta r)^2}}\). For effective isolation, TR < 1 requires \(r > \sqrt{2}\).
Uploaded by: Fani Warraich
Geography
QUESTION #6345
Question 3167
The concept of 'time-space convergence' in economic geography refers to:
Correct Answer Logic:
Time-space convergence describes how transport/communication improvements reduce travel time between places, making them functionally closer despite unchanged physical distance. A trip taking weeks in the 1800s now takes hours, facilitating globalization.
Uploaded by: Fani Warraich
Correct Answer Logic:
From \(\vec{a} \times \vec{c} + \vec{b} = \vec{0}\), we get \(\vec{a} \times \vec{c} = -\vec{b}\). Taking dot product with \(\vec{a}\): \(\vec{a} \cdot (\vec{a} \times \vec{c}) = -\vec{a} \cdot \vec{b}\). Since \(\vec{a} \cdot (\vec{a} \times \vec{c}) = 0\), we have \(\vec{a} \cdot \vec{b} = 0\), which checks: \((1)(-1)+(-1)(1)+(0)(1) = 0\). Nope: \(\vec{a} = \hat{i}-\hat{j}\) (only 2D) and \(\vec{b} = \hat{i}+\hat{j}+\hat{k}\), so \(\vec{a} \cdot \vec{b} = 1-1 = 0\). Good. Taking magnitude: \(|\vec{a} \times \vec{c}| = |\vec{b}| = \sqrt{3}\). Also \(|\vec{a} \times \vec{c}|^2 = |\vec{a}|^2|\vec{c}|^2 - (\vec{a} \cdot \vec{c})^2\), so \(3 = 2|\vec{c}|^2 - 16\), giving \(|\vec{c}|^2 = \frac{19}{2}\).
Uploaded by: Fani Warraich
Boilers Mechanical Engineering
QUESTION #3981
Question 3169
The 'Economizer' in a boiler system is used to heat:
Correct Answer Logic:
Economizers improve efficiency by recovering waste heat from exhaust gases to pre-heat feed water.
Uploaded by: Fani Warraich
Reading and Writing (Module-1)
QUESTION #5340
Question 3170
In 1953, James Watson and Francis Crick discovered the double-helix structure of DNA. This ______ changed the field of genetics forever. Which choice completes the text with the most logical and precise word?
Correct Answer Logic:
A major scientific discovery is best described as a 'breakthrough.'
Uploaded by: Fani Warraich
Pharmacology and Toxicology
QUESTION #3853
Question 3171
Through which mechanism does allopurinol lower serum uric acid levels?
Correct Answer Logic:
Allopurinol inhibits xanthine oxidase, thereby reducing the enzymatic conversion of hypoxanthine and xanthine to uric acid.
Uploaded by: Fani Warraich
Ability / HR / Governance / Special Education
QUESTION #1903
Question 3172
Under Rule 3(d) retention in service of a government servant engaged in subversive activities must be what for action to be taken?
Correct Answer Logic:
Rule 3(d) specifically requires that the government servant's retention in service must be prejudicial to national security as the additional condition for action on grounds of subversive activities or disclosure of official secrets.
Uploaded by: Fani Warraich
Math Physics Chemistry Biology
QUESTION #4199
Question 3173
Which of the following best describes the relationship between endoplasmic reticulum (ER) and Golgi apparatus?
Correct Answer Logic:
ER synthesizes proteins/lipids that are transported to Golgi apparatus for processing and packaging.
Uploaded by: Fani Warraich
Correct Answer Logic:
Section 48A(2) states: 'the Revising Authority shall issue a notice to him to appear before it within fifteen days and require him to sign a declaration... regarding his belief about the absolute and unqualified finality of the Prophethood of Muhammad (peace be upon him).'
Uploaded by: Fani Warraich
Physics
QUESTION #402
Question 3175
A wire has resistance 100 Ohm at 0?C and 200 Ohm at 100?C. What is its temperature coefficient in K???
Correct Answer Logic:
? = (R??R?)/(R??T) = 100/(100?100) = 0.01 K??, but answer key shows D
Uploaded by: Fani Warraich
Correct Answer Logic:
$\frac{\partial Q}{\partial x} = 2x^3y$, $\frac{\partial P}{\partial y} = 2xy^3$. So $\iint_R (2x^3y - 2xy^3) dA = \int_0^3\int_0^2 (2x^3y - 2xy^3) dy dx = 18$.
Uploaded by: Fani Warraich
Paper-II (Pharmacognosy and Pharmaceutics-I)
QUESTION #2976
Question 3177
The 'Ebers Papyrus' is an ancient document related to the pharmacy of which civilization?
Correct Answer Logic:
The Ebers Papyrus (1550 BC) is one of the most important pharmaceutical records of Ancient Egypt.
Uploaded by: Fani Warraich
General Knowledge
QUESTION #8828
Question 3178
The constellation 'Southern Cross' (Crux) consists of how many main stars?
Correct Answer Logic:
'In addition' signals that incorporating African music is a second example of how Coleridge-Taylor emphasized his mixed-race ancestry.
Uploaded by: Fani Warraich
Physics
QUESTION #7321
Question 3180
The velocity of a particle is given by $v = At + Bt^2$, where $A$ and $B$ are constants. The distance travelled between $t = 1\text{ s}$ and $t = 2\text{ s}$ is:
Correct Answer Logic:
$x = \displaystyle\int_1^2 v\,dt = \int_1^2 (At + Bt^2)\,dt = \left[\dfrac{At^2}{2} + \dfrac{Bt^3}{3}\right]_1^2$
$= \left(\dfrac{4A}{2} + \dfrac{8B}{3}\right) - \left(\dfrac{A}{2} + \dfrac{B}{3}\right) = \mathbf{\dfrac{3A}{2} + \dfrac{7B}{3}}$
Uploaded by: Fani Warraich
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