A. Si
B. Sc
C. None of these
D. Sn
Explanation
Elements that form XF₄ compounds typically belong to Group 14 (like Sn, Si, Ge), which can form stable tetrahalides (XF₄). Sc (Scandium) belongs to Group 3 and does not form XF₄ type compounds. Show/Hide Explanation
A. Foil
B. None of these
C. Narrator
D. Protagonist
Explanation
The protagonist is the main character in a drama, around whom the story revolves. They face conflicts and drive the plot forward. Show/Hide Explanation
A. Built
B. Are building
C. Will have built
D. None of these
Explanation
By next year, they will have built their new house. اگلے سال تک ، وہ اپنا نیا مکان تعمیر کرلیں گے۔ " By next year " indicates a future perfect tense structure. " Will have built " correctly expresses an action that will be completed before a specific time in the future . Show/Hide Explanation
آئن اسٹائن کے ذریعہ متعارف کروائے جانے والے مندرجہ ذیل میں سے کون سے تصورات نے جدید کوانٹم میکانکس کی بنیاد رکھی؟
A. Principle of Relativity
B. Photoelectric effect
C. None of these
D. Theory of General Relativity
Explanation
Einstein's explanation of the photoelectric effect (1905) introduced the concept of quantized energy (photons) , laying the foundation for quantum mechanics. This discovery led to Einstein receiving the Nobel Prize in Physics (1921) and helped develop wave-particle duality in quantum theory. Show/Hide Explanation
مندرجہ ذیل میں سے کون سا زیادہ توانائی بخش ہے؟
A. 4s
B. 4d
C. None of these
D. 4f
Explanation
In the same principal energy level (n = 4), 4f has the highest energy due to its complex shape and shielding effects. The energy order follows: 4s < 4p < 4d < 4f. Show/Hide Explanation
ٹھوس مادہ کے اعتدال پسند خشک ہونے کے لئے سب سے موزوں درجہ حرارت ______ ہے؟
A. 320°C
B. 220°C
C. 120°C
D. None of these
Explanation
Moderate drying of solid substances is typically done at 120°C to remove moisture without decomposition. Higher temperatures may cause degradation of heat-sensitive materials. Show/Hide Explanation
فینول سائکلوہیکسنول سے بہتر برونسٹڈ ایسڈ ہے جس کی بڑی وجہ _____ ہے؟
A. Phenol is able to stabilize the anion formed in the reaction by resonance
B. The phenyl group is an electron withdrawing group by induction, which stabilizes the action formed in the reaction
C. None of these
D. It is a better proton donor
Explanation
Phenol's conjugate base (phenoxide ion) is stabilized by resonance , spreading the negative charge over the benzene ring. Cyclohexanol lacks resonance stabilization , making its conjugate base less stable and less acidic. Show/Hide Explanation
A. Rotational energy
B. Resonance broaden the absorption
C. Hyperconjugation resonance broadens
D. Hydrogen bonding broadens the absorption
Explanation
Hydrogen bonding in CH3OH causes a range of bond strengths, leading to broad absorption in the IR spectrum . This disrupts uniform vibrational energy levels, spreading the absorption over a wider frequency range. Show/Hide Explanation
A. sp^3 d
B. sp^3
C. None of these
D. sp^2
Explanation
In BH₃ , boron forms three sigma bonds with hydrogen and has no lone pairs, leading to sp² hybridization . The molecular geometry is trigonal planar , with 120° bond angles. Show/Hide Explanation
سب سے زیادہ کیلوری کی قیمت کے ساتھ نامیاتی غذائی اجزاء ______ ہے؟
A. Fat
B. Protein
C. Sugar
D. None of these
Explanation
Fat provides 9 kcal per gram . Protein and carbohydrates provide 4 kcal per gram. Show/Hide Explanation
