SPSC CHEMISTRY 25 YEARS PAST PAPERS
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چار آپشن میں سے کسی ایک پر کلک کرنے سے جواب سرخ ہو جائے گا۔
محوری لمبائی اور کرسٹل کے یونٹ سیل کے بین محوری زاویوں کو _____ کے نام سے جانا جاتا ہے؟
- Crystal system
- Coordination number
- Lattice constants
- None of these
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Explanation
Lattice constants define the dimensions and angles of a unit cell in a crystal structure.They determine the geometry and symmetry of a crystalline solid.
- √l(l + 1) h/2π
- √l(l + 2) h/2π
- √l(l + 3) h/2π
- None of these
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Explanation
In Schrödinger wave mechanics, angular momentum is quantized as L = √l(l + 1) h/2π, where l is the azimuthal quantum number.This differs from Bohr's model, which assumes L = nh/2π without considering quantum wave behavior.
مندرجہ ذیل میں سے کون سے جوہری کا سب سے بڑا قطر ہے؟
- I
- Br
- Cl
- None of these
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Explanation
As you move down a group in the periodic table, atomic size increases due to the addition of electron shells.Iodine is below bromine, chlorine, and fluorine, so it has the largest atomic diameter.
رد عمل کی ترتیب _______ کے طور پر بیان کی گئی ہے؟
- Number of reactants
- Power of concentration terms in the rate law equation
- Rate of reactions
- None of these
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Explanation
The order of reaction is defined as the sum of the powers of the concentration terms in the rate law equation.
It shows how the reaction rate depends on the concentrations of reactants.
مندرجہ ذیل میں سے کون سا مکمل طور پر بے ساختہ ہے؟
- Abestose
- Glass fiber
- Wool
- None of these
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Explanation
Glass fiber is completely amorphous.
It is made of fine fibers of glass, and glass.
In general, is an amorphous solid, meaning it lacks a regular crystalline structure.
ربڑ کی واولکنائزیشن کیا ہے؟
- Converts its plasticity into elasticity
- Increases its oil and solvent resistance
- Increases its ozone and oxygen reactivity
- None of these
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Explanation
Vulcanization is a chemical process in which rubber is heated with sulfur, causing cross-links to form between polymer chains.
This process turns the rubber from a soft, flexible material into a more durable, elastic one.
- H ----- F
- H ----- OH
- H ----- NH3
- None of these
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Explanation
The polarity of a bond is determined by the difference in electronegativity between the two atoms involved.Fluorine (F) is one of the most electronegative elements, much more so than hydrogen (H).It leading to a significant electron density shift towards fluorine, making the H ----- F bond highly polar.
- 512 liters
- 0.8 liter
- 800 liters
- None of these
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Explanation
To find the volume, we need to divide the mass by the density.Mass = 640g
Density = 0.8g/ml
First, convert the density to g/L by multiplying by 1000 (since 1L = 1000ml):
Density = 0.8g/ml × 1000 = 800g/L
Now, divide the mass by the density:
Volume = Mass ÷ Density
= 640g ÷ 800g/L
= 0.8 L
- Nitrogen-14
- Boron-14
- Oxygen-14
- None of these
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Explanation
Beta decay of carbon-14 involves the conversion of a neutron into a proton, emitting an electron (beta particle).This changes the atomic number from 6 (carbon) to 7 (nitrogen), forming nitrogen-14.
- 5
- 3
- 0
- None of these
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Explanation
In elemental form (N₂), nitrogen is in its natural, uncombined state.The oxidation number of any element in its pure form is always 0.
