EVERYDAY SCIENCE
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چار آپشن میں سے کسی ایک پر کلک کرنے سے جواب سرخ ہو جائے گا۔
کون سا آئن سب سے زیادہ غیر جفت الیکٹران رکھتا ہے؟
- Mn²⁺
- Fe²⁺
- Co²⁺
- None of these
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Explanation
- Unpaired electrons depend on d-orbital electronic configuration.
- Mn²⁺ has configuration: [Ar] 3d⁵.
- According to Hund’s rule, all five d-electrons remain unpaired.
Last verified on 19-05-2026
کون سا مالیکیول 120° کے قریب بانڈ اینگل رکھتا ہے؟
- CH₄
- NH₃
- BF₃
- None of these
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Explanation
- Bond angle depends on molecular geometry and electron pair repulsion.
- Trigonal planar molecules have bond angles close to 120°.
- BF₃ has no lone pair on central atom, so perfect trigonal planar shape.
Last verified on 19-05-2026
سب سے زیادہ آئنک خصوصیت کس میں ہے؟
- KBr
- LiF
- NaCl
- None of these
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Explanation
- Ionic character depends on electronegativity difference between atoms.
- Greater difference → more ionic nature.
- Lithium (Li) and Fluorine (F) have a very large electronegativity gap.
- Small size of Li⁺ also increases polarizing power, but F⁻ is very electronegative.
- So LiF shows the strongest ionic bond among given options.
Last verified on 19-05-2026
ایتھانول اور ایتھانوئک ایسڈ کے ردِ عمل سے بننے والا ایتھائل ایسیٹیٹ کس قسم کا ردِ عمل ہے؟
- Neutralization
- Hydrolysis
- Esterification
- None of these
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Explanation
- Ethyl acetate is an ester compound.
- It is formed when an alcohol reacts with a carboxylic acid.
- Ethanol + ethanoic acid undergo a condensation reaction.
- Water is removed during the formation of ester.
- This process is commonly called ester formation.
Last verified on 19-05-2026
خود بخود ہونے والے ردِ عمل کے لیے گِبس فری انرجی کیا ہوتی ہے؟
- Negative
- Positive
- Zero
- None of these
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Explanation
- Gibbs free energy (ΔG) determines spontaneity of a reaction.
- A reaction is spontaneous when it can proceed on its own.
- For spontaneity, energy must be released during the process.
- This means the system moves toward lower energy state.
- Therefore, ΔG must be less than zero.
Last verified on 19-05-2026
- Decrease
- Remain constant
- Increase
- None of these
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Explanation
- Gibbs free energy change depends on reaction quotient (Q).
- Relation: ΔG = ΔG° + RT ln Q.
- When Q increases, ln Q increases.
- This makes ΔG more positive.
- So the system becomes less spontaneous in forward direction.
Last verified on 19-05-2026
کون سا آربٹل سب سے زیادہ مؤثر نیوکلیئر چارج محسوس کرتا ہے؟
- 3s
- 3p
- 3d
- None of these
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Explanation
- Effective nuclear charge (Zₑff) is the net positive charge felt by an electron.
- It increases when shielding is less and penetration is higher.
- For a given shell (n = 3), penetration order is: 3s > 3p > 3d.
- 3s electrons are closest to the nucleus and least shielded.
- Therefore, they experience the strongest attraction from the nucleus.
Last verified on 19-05-2026
- Inversion of configuration; rate depends on both substrate and nucleophile
- Racemization; rate depends only on substrate
- Retention of configuration; rate depends only on nucleophile
- None of these
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Explanation
- SN2 is a bimolecular nucleophilic substitution reaction.
- It occurs in a single step with a backside attack by nucleophile.
- This causes inversion of configuration (Walden inversion).
- Rate depends on both substrate and nucleophile concentration.
- It is a second-order reaction.
Last verified on 19-05-2026
کرومیم کی زمینی حالت میں الیکٹرانک ترتیب کیا ہے؟
- [Ar] 3d⁴ 4s²
- [Ar] 3d⁵ 4s¹
- [Ar] 3d⁶ 4s⁰
- None of these
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Explanation
- Chromium (Cr) has atomic number 24.
- Expected configuration is [Ar] 3d⁴ 4s², but it is not stable.
- One 4s electron shifts to 3d to achieve stability.
- Half-filled d-subshell (3d⁵) is more stable due to symmetry and exchange energy.
- So chromium shows an exception in electronic configuration.
Last verified on 19-05-2026
بوران کی پہلی آئنائزیشن انرجی بیریلیم سے کم کیوں ہے۔ الیکٹران کس مدار سے نکلتا ہے؟
- 2p orbital
- 1s orbital
- 2s orbital
- None of these
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Explanation
- Ionization energy is the energy needed to remove an electron from an atom.
- Beryllium (Be) has configuration: 1s² 2s² (stable 2s subshell).
- Boron (B) has configuration: 1s² 2s² 2p¹.
- The electron in boron is removed from a higher energy 2p orbital.
- 2p electron is farther and less tightly held than 2s, so easier to remove.
Last verified on 19-05-2026
