Pakistan MCQs

Diffraction is strongest when the opening or obstacle is comparable to wavelength.
It is a general wave property.

Electrolysis drives oxidation and reduction at electrodes.
It is used in plating, refining, and chemical production.

Standing waves form from superposition of opposite traveling waves.
Nodes remain at zero displacement.

PH=-log(1×10^-3).
The result is 3.

Higher-frequency sound is perceived as higher pitch.
Pitch perception is related to but not identical with frequency.

POH=-log(1×10^-4).
The result is 4.

At 25°C, pH+pOH=14.
POH=14-5 = 9.

Moles NaOH=0.0200×0.50=0.0100 mol.
The HCl concentration is 0.0100/0.0250=0.40 M.

More exposed particles are available for collision.
Powders often react faster than large pieces.

Oxidation and reduction occur together.
The oxidized species donates electrons.

A reduced species accepts electrons.
Reduction accompanies oxidation.

The oxidizing agent accepts electrons.
Its oxidation number decreases.