نوبل گیسیں ______ کی وجہ سے اتنے ناقابل عمل ہیں؟
A. High bond energy
B. High Ionization potential
C. None of these
D. Complete octet
Explanation
Noble gases have a full outer electron shell, making them stable and unreactive . This complete octet configuration prevents them from easily forming bonds. Show/Hide Explanation
A. Copper
B. None of these
C. Lead
D. Aluminum
Explanation
Aluminum and Chromium both have similar oxidation states (+3) and chemical properties. Al³⁺ can substitute Cr³⁺ in Cr₂O₃ due to comparable ionic radii and charge. Show/Hide Explanation
کم سے کم مستحکم کاربنین _____ ہے؟
A. (CH₃)₃C⁻
B. (CH₃)₂C⁻
C. None of these
D. CH₃⁻
Explanation
The tertiary carbanion (CH₃)₃C⁻ is the least stable because the negative charge is not effectively stabilized by resonance or inductive effects. Tertiary carbanions are highly unstable compared to secondary and primary carbanions. Show/Hide Explanation
A. 3.5 kJ
B. 3550 kJ
C. None of these
D. 355 kJ
Explanation
To boil 1 liter of water from 15°C to 100°C, the energy required is:
Q = mcΔT
= 1 kg × 4.18 kJ/kg°C × (100°C - 15°C)
= 1 × 4.18 × 85
= 355 kJ
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بڑھتی ہوئی تعدد کے سلسلے میں ورنکرم علاقوں کا صحیح حکم _____ ہے؟
A. None of these
B. RF, IR, ViS, UV
C. UV, ViS, IR, RF
D. UV,ViS, RF, IR
Explanation
RF (Radio frequency) has the lowest frequency, followed by IR (Infrared), ViS (Visible spectrum), and then UV (Ultraviolet), which has the highest frequency. This order follows the sequence of increasing frequency in the electromagnetic spectrum. Show/Hide Explanation
A. Bi^3+, Sn^4+
B. Al^3+, Hg^2+
C. Cu^2+, Zn^2+
D. None of these
Explanation
H₂S in dilute HCl is used to separate metal ions based on their solubility as sulfides. Bi³⁺ and Sn⁴⁺ do not separate easily. Because they both form insoluble sulfides under similar conditions. Show/Hide Explanation
A. 10
B. 8
C. None of these
D. 4
Explanation
For a strong acid with a high K a K_a K a , it fully ionizes in water. pH is calculated as p H = − log [ H + ] pH = -log[H^+] [ H + ] = 10 − 4 [H^+] = 10^{-4} pH = 4.
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برقی مقناطیسی لہروں کی رفتار ______ ہے؟
A. 3 × 10⁸ m/s
B. None of these
C. 1 × 10⁸ m/s
D. 1 × 10⁶ m/s
Explanation
The velocity of electromagnetic waves (EM waves) in a vacuum is approximately 3 × 10⁸ meters per second. This speed is constant for all EM waves, including light, radio waves, and X-rays, in a vacuum. Show/Hide Explanation
A. Water will freeze
B. It will decompose into H₂ and O₂
C. None of these
D. Water will boil
Explanation
On the moon, there is no atmospheric pressure , which lowers the boiling point of water. Since the water is at 300°C, it will immediately boil once the lid is opened. Show/Hide Explanation
دھاتوں کی غیر مساوی توسیع آپریشن کو ____ ممکن بناتی ہے؟
A. None of these
B. Hygrometers
C. Aneroid barometer
D. Thermostats
Explanation
Thermostats work based on the unequal expansion of metals in a bimetallic strip. This property helps in regulating temperature by switching devices on or off. Show/Hide Explanation
