Explanation

The critical angle for water (from water to air) is approximately 48.6°, rounded to 49°.

This is the angle of incidence above which total internal reflection occurs when light travels from water to air.

Explanation

Parentheses ( ) are used to add extra information or clarification within a sentence.

In "(the architect)", parentheses enclose additional but non-essential information about Hameed Ullah Khan.

Explanation

Expansion of metal on heating is a physical change because it does not alter the metal’s chemical composition.

When cooled, the metal returns to its original size, showing that the change is reversible.

Explanation

A solution is a homogeneous mixture where two or more substances are evenly distributed.

It consists of a solute (dissolved substance) and a solvent (the substance in which the solute dissolves).

Explanation

Rhizopus is a genus of mold that belongs to the kingdom Fungi.

It is commonly found on bread, fruits, and decaying organic matter.

It reproduces through spores.

It is known for its role in food spoilage and some industrial applications.

Explanation

حلف الفضول ایک معاہدہ تھا جس میں قریش نے مظلوموں کی مدد کرنے اور ان کے حقوق کا تحفظ کرنے کا عہد کیا تھا۔

حضور اکرم صلی اللہ علیہ وسلم نے اس معاہدے کو پسند فرمایا کیونکہ اس میں انصاف اور مظلوموں کی مدد کا وعدہ کیا گیا تھا۔

Explanation

Let x be the number of years in the future. Then:

Father’s age = 41 + x, Son’s age = 9 + x

Set up the equation: 41 + x = 3(9 + x)

→ 41 + x = 27 + 3x → 14 = 2x → x = 7 years.

Explanation

This is a statement of the Triangle Inequality Theorem, which states that the sum of any two sides of a triangle must be greater than the third side.

It ensures the sides form a valid triangle.

Explanation

Aestivation is a state of inactivity or dormancy that animals enter during hot or dry seasons to conserve energy.

Hibernation, in contrast, occurs during winter when animals become inactive to survive cold temperatures.

Explanation

Polythene bags are synthetic plastics that do not decompose naturally, taking hundreds of years to break down.

Unlike organic materials like feathers, paper, and wood, polythene bags contribute to environmental pollution.