Materials and Their Applications

The cement industry requires limestone (calcium carbonate) and clay (silica and alumina sources) as the two primary raw materials. These are heated in a kiln to form clinker, which is then ground with gypsum to produce cement. Individual materials alone (A or C) are insufficient, and gypsum (option B) is added later, not as a primary raw material.

Flint glass has a higher refractive index compared to crown glass, making it ideal for prisms and lenses where greater light bending is required. It contains lead oxide, which increases its refractive power and dispersion properties.

Yes,  it is correct.

Oiled paper is a translucent medium, i.e.  it allows the light to partially pass through it. This is the correct option.

Igloos are traditional shelters built by Inuit people using blocks of compressed snow and ice. The insulating properties of snow help trap air and maintain warmth inside, making ice the correct material choice.

Steel is the most elastic material among the options. Elasticity is defined as the ability to return to original shape after deformation. While rubber stretches more easily, steel has a higher elastic modulus and can undergo larger stress while still returning to its original shape. Wet clay deforms plastically (permanently), and plastic shows viscoelastic behavior with hysteresis.

This is an analogy question. Vitro is a prefix relating to glass (as in 'vitroceramic'). Similarly, Ligno is a prefix relating to wood (from 'lignin', the organic polymer in wood). Just as vitro-glass combinations involve glass, ligno-wood combinations involve wood.

This is the correct option because both gold and aluminium are lustrous metals.

This is the correct answer. All these objects are opaque as you cannot see through these objects.

The relationship is natural material:product made from it. Quartz is used to make radio components (like crystal oscillators). Similarly, gypsum is used to make cement (it's a key ingredient in Portland cement). The other options (powder, stone powder, glass) are not the primary industrial product of gypsum.

This is the Asian Paints slogan in Hindi, meaning "walls will remain time-proof." Asian Paints is India's largest paint company and this campaign emphasized the durability of their paint products. Fevicol and Berger are other paint/adhesive companies but this specific tagline belongs to Asian Paints.

Butter paper is a translucent object. Translucent object transmits only partial light through it.

Fer means iron, lock is made of iron.