Everyday Science

Gases expand to fill all the available space in a container, unlike solids and liquids which have fixed or limited shapes. Therefore, the correct answer is Gas.

The safe moisture content for storing cereals is generally around 10% to prevent mold growth and spoilage. Higher moisture levels like 14% or above increase the risk of fungal contamination and reduce shelf life.

Bone ash primarily contains calcium phosphate compounds, not calcium sulphate. The main chemical components of bone ash are about 55% calcium oxide (CaO) and 42% phosphorus pentoxide (P2O5), which correspond to calcium phosphate phases such as tricalcium phosphate (Ca3(PO4)2) or hydroxyapatite (Ca5(OH)(PO4)3). Calcium sulphate is not a primary component of bone ash. Therefore, none of the given options A (calcium sulphate), B (phosphoric sulphate), or C (Calcium sulphate) correctly describe the primary content of bone ash. The correct answer is D (None of these).

Tomatoes typically contain about 90% water by weight, making option B the most accurate choice. Option A (94%) is slightly higher than the commonly accepted value.

Heavy mechanical complexes typically use large amounts of water primarily for cooling purposes to dissipate heat generated during operation.

Air movement from one location to another in the atmosphere is primarily caused by convection, which involves the transfer of heat by the movement of fluids such as air. Radiation and conduction are different heat transfer processes, and electromagnetic induction is unrelated to air movement.

Caffeine, nicotine, and piperine are all naturally occurring compounds found in plants, whereas saccharin is an artificial sweetener synthesized chemically and not derived from plants.

Hepatitis and Polio are both caused by viruses. Hepatitis refers to viral infections affecting the liver, and Polio is caused by the poliovirus, making 'Virus' the correct answer.

A man's weight is the gravitational force on his mass and remains constant regardless of his position (sitting, standing, or lying down). The total force exerted on the Earth does not change with posture. What changes is the pressure (force per unit area) due to the difference in contact area with the ground or supporting surface. Standing typically produces the highest pressure on the feet because the contact area is smallest, sitting distributes the weight over a larger area (seat), and lying down distributes it over an even larger area (back and legs). Therefore, the man does not press more weight on Earth in any particular position; the weight is the same in all positions. Hence, the correct answer is 'D' (None of these).

Dead plants are biodegradable because they can be broken down naturally by microorganisms. Cans and glass are not biodegradable as they do not decompose easily in the environment.