SPSC CHEMISTRY 25 YEARS PAST PAPERS
SPSC 5 years Past Papers Click here
Show Answers
چار آپشن میں سے کسی ایک پر کلک کرنے سے جواب سرخ ہو جائے گا۔
جب ایک دوسرے پر دو کیوب دبائے جاتے ہیں تو وہ ایک مکعب بنانے کے لئے متحد ہوجاتے ہیں۔ مندرجہ ذیل میں سے کون سی قوت ان کو ایک ساتھ رکھنے کی ذمہ دار ہے؟
Hydrogen bond formation
Covalent attraction
Vander Wall's forces
None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
When two cubes are pressed together, Van der Waals forces (weak intermolecular forces) help them stick. These forces arise due to temporary dipoles and dispersion forces between molecules.
When the temperature is high and pressure is low
When the temperature is low
When both the temperature and pressure are low
None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
A real gas behaves like an ideal gas at high temperature (molecules have enough kinetic energy to overcome intermolecular forces) and low pressure (molecules are far apart, reducing interactions). Under these conditions, the gas follows the ideal gas equation P V = n R T PV = nRT .
وہ کمپلیکس جن میں تین سے کم ڈی الیکٹران ہوتے ہیں وہ _____ ہیں؟
Labile
Unstable
Inert
None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
Complexes with fewer than three d-electrons tend to be labile . It means they undergo fast ligand exchange reactions. This is because they experience weaker crystal field stabilization and lower energy barriers for bond rearrangement.
Hybridization
M.O theory
VSEPR theory
None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
BF₃ has a trigonal planar geometry with 120° bond angles, which cannot be explained by pure p orbitals (90°) . The concept of sp² hybridization explains the observed bond angles by mixing one s and two p orbitals.
Fusion
Alpha radiation
Fission
Beta radiation
None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
Uranium-238 (238 U ^{238}U undergoes alpha decay, emitting an alpha particle (4 H e ^4He , reducing its atomic number by 2 and mass number by 4. This transforms it into Thorium-234 (234 T h ^{234}Th
جب ایک نیوکلئس بیٹا ذرات کا اخراج کرتا ہے تو ، والدین اور بیٹی نیوکللی ______ ہوتے ہیں؟
Isotones
Nuclear isomers
Isobars
None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
In beta decay (β − beta^- , a neutron converts into a proton, increasing the atomic number by 1 while keeping the mass number the same. Parent and daughter nuclei have the same mass number (A) but different atomic numbers (Z), making them isobars.
Dipole moment
Fewer electrons than O2
Two covalent bonds
None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
Water (H 2 O H_2O dipole moment , leading to strong hydrogen bonding between molecules. This increases its critical temperature compared to O 2 O_2 weak intermolecular forces.
sp^3 d
sp^3
sp^2
None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
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.
تیزابیت کے بعد جو ڈھانچہ باقی رہتا ہے وہ پروٹون کو ____ کہتے ہیں؟
Conjugate salt
Conjugate base
Conjugate acid
None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
When an acid donates a proton (H + H^+ conjugate base. For example, HCl (acid) gives up H + H^+ conjugate base ).
It is chemical reactive
Its Z is odd
It is odd-odd nucleus
None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
50P15 (Phosphorus-50) has both an odd proton number (Z = 15) and an odd neutron number (N = 35), making it unstable. Most odd-odd nuclei are unstable due to nuclear pairing effects.
