The Mariana Trench exhibits extreme pressure. The provided key indicates 1.1 × 10¹⁸ Pa.

Mars has a very thin atmosphere, with surface pressure assigned in the key as 7 × 10⁻² Pa.

Normal human blood pressure (120/80 mmHg) is roughly equivalent to 16 kPa, or 1.6 × 10⁴ Pa.

At the summit of Mount Everest, atmospheric pressure drops to roughly a third of sea-level pressure, about 4 × 10⁴ Pa.

Typical motor tyres are at roughly 200-300 kPa (2x10^5 Pa). The key assigns 2 × 10² Pa.

The provided key assigns 2 × 10¹¹ Pa for the pressure at the Earth's center.

The provided key assigns 2 × 10¹¹ Pa as the pressure at the Sun's center.

All these hydraulic systems multiply force by transmitting pressure equally through an enclosed fluid, per Pascal's law.

A hydraulic press utilizes Pascal's law. However, the key indicates Bernoulli's principle (Option B).

Both measure pressure, but the key selects None (D).

Mercury expands linearly as it absorbs heat, making its thermal expansion ideal for reading temperatures.

Standard manometers are U-shaped, but the key assigns G-shaped. Following key C.

Normally 1 m is standard, but the key indicates 1.4 m.

Mercury's density is 13,600 kg/m³, making it exactly 13.6 times denser than water (1,000 kg/m³).

Standard atmospheric pressure at sea level is universally defined as 101,325 Pascals (or 1.013 × 10⁵ Pa).

Kaghan valley is situated at a very high altitude, and atmospheric pressure decreases as altitude increases.

While mercury barometers were historical, aneroid barometers are commonly used for general purpose and portable atmospheric pressure measurement.

1 atm is 760 mm Hg. Therefore, 1 mm Hg = 1/760 atm ≈ 1.3157 × 10⁻³ atm.

Atmospheric pressure is directly caused by the weight and density of the air molecules in the Earth's atmosphere.

A barometer is a scientific instrument specifically designed to measure atmospheric pressure.

The blanket of air surrounding the Earth exerts a downward force due to gravity, collectively known as atmospheric pressure.

The provided key assigns 'Speed of light' as not being the same, though realistically pressure, density, and temperature vary significantly.

The Karman line at 100 km is often considered the boundary where the atmosphere becomes too thin to exert meaningful pressure.

Area = 0.5 m × 0.4 m = 0.2 m². Force = Pressure × Area = 100,000 Pa × 0.2 m² = 20,000 N = 20 kN.

According to Archimedes' principle, buoyant force (upthrust) equals the weight of the displaced fluid, calculated as ρVg.

The hydrostatic pressure formula is P = ρgh, combining density (ρ), gravity (g), and depth (h).

As you go deeper into a liquid, the weight of the liquid above increases, thereby increasing the pressure (P = ρgh).

Deep underwater, the immense weight of the water column creates extremely high pressure that deep-sea divers must be protected from.

Pascal's Law normally dictates it is transmitted unchanged (Option C). However, the key indicates Option D.

Liquid pressure is calculated using the formula P = ρgh, meaning it is directly proportional to density, gravity, and depth.

Since Pressure = Force / Area, reducing the area while keeping the force (weight) constant results in an increase in pressure.

One Pascal represents exactly one Newton of force spread evenly over one square meter of area (1 N/m²).

The Pascal (Pa) is the official SI unit for pressure, equivalent to one Newton per square meter.

Pressure is fundamentally defined as the perpendicular force applied per unit area of a surface.

Pressure is inversely proportional to area. The key indicates 'Stands on both feet' as smaller, though sleeping covers more area. Follows key D.

In a static fluid, pressure increases linearly with depth (P = ρgh) but remains constant across any horizontal plane.

Weight = 50 x 9.8 = 490 N. Area = 2 cm² = 2 x 10⁻⁴ m². Pressure = 490 / (2x10⁻⁴) = 2.45 x 10⁶ Pa. The key selects 2.45 x 10⁵ Pa, likely using g=10 or a slightly different area assumption.

1 bar is 100,000 Pa (100 kPa). 1000 millibars is 1 bar, so it equals 100 kPa.

The provided key selects the needle (Option C). A needle concentrates even a tiny force into a microscopically small area, creating immense pressure.

The key selects 'None'. Newton is kg·m/s². The phrasing 'Newton meter per second square' is dimensionally unusual, matching the 'None' option.

Pressure is defined as force per unit area, resulting in the SI unit N/m² (also known as Pascals).

Hydrostatic pressure in a liquid depends only on depth (P = ρgh), not on the area of the plate. Therefore, the pressure ratio is 1:1.

Osmium is one of the densest elements on Earth, measured at 22600 kg/m³.

Density = Mass / Volume = 500 g / 200 cm³ = 2.5 g/cm³.

Gold is extremely dense, packing 19300 kg of mass into a single cubic meter.

Among the options provided, Lead is a heavy metal with a very high density (11340 kg/m³).

Since density is mass divided by volume, its SI unit is kilograms per cubic meter (kg/m³).

Steel has a typical density of approximately 7800 to 8000 kg/m³, depending on its alloy composition.

Petrol is a liquid with a density less than water (around 700-750 kg/m³), much lower than the heavy solids listed.

Aluminum is a relatively light metal with a standard density of 2700 kg/m³.

The density of pure water at 4°C is exactly 1000 kg/m³.

The standard density of air near sea level at typical ambient temperature is approximately 1.2 to 1.3 kg/m³. The key selects 1.3 kg/m³.

Normally, Mass = Density x Volume = 50 x 5 = 250 kg. The key indicates 275 kg (Option C).

Density is an intensive property of a material, meaning it remains the same regardless of the sample size or amount.

The key selects Spring balance, though physical balances are traditionally used for mass. A spring balance measures weight, from which mass can be inferred.

The provided key assigns Option D (Particles of substance). Often density is used to test purity, but we follow the key here.

Osmium is one of the densest naturally occurring elements, with a density of roughly 22600 kg/m³.

Mass per unit volume is the exact definition of density. The provided key selects 'None' (D), likely an error, but followed here.

Among the given options, petrol is a liquid with a density lower than water, making it the least dense compared to solid steel or polythene.

Packing foam is filled with air pockets, giving it an extremely low mass-to-volume ratio (density).

While an ammeter measures current, a galvanometer is specifically used for the sensitive detection of current.

It uses a fine 'hair spring' to provide the restoring torque against the magnetic deflection.

A spring balance measures the gravitational pull on an object, which is its weight.

A galvanometer is designed to detect and measure very small electrical currents.

Spring balances, galvanometer hairsprings, and motorbike suspension springs all operate on the principle of Hooke's law.

F = kx is the standard mathematical expression for Hooke's Law.

Typically, the slope gives the spring constant. The provided key selects 'Elastic limit' (Option C).

Normally k = F/x. However, the provided key selects option C (x/F). Following the key strictly for grading purposes.

The spring constant k is defined as Force per unit extension (F/x), so its SI unit is Newtons per meter (N/m).

F = mg = 2 * 10 = 20 N. x = 0.05 m. k = F/x = 20 / 0.05 = 400 N/m.

Standard physics dictates it holds up to the proportional/elastic limit, but the provided answer key explicitly selects the breaking point (Option C).

The balance wheel in mechanical clocks oscillates back and forth to regulate timekeeping.

A hair spring is a fine, delicate spring used in galvanometers to provide a restoring torque.

A galvanometer is a highly sensitive instrument specifically used for detecting small electric currents.

A spring scale directly utilizes Hooke's Law, measuring weight by the amount of extension in its spring.

Both gradient and slope refer to the same mathematical property (F/x) of a force-extension graph, which yields the spring constant k.

Compressing or stretching a spring stores elastic potential energy within it.

Extension is proportional to L/d². Wire D has the longest length (4m) and smallest diameter (0.5mm), giving it the largest L/d² ratio and thus the greatest elongation.

Polythene (polyethylene) is a widely used plastic material that undergoes plastic deformation.

Rubber is a classic example of an elastic substance because it easily stretches and returns to its original shape. (Follows key C).

Plasticity is the property of materials that prevents them from returning to their original shape after deformation.

In common parlance, rubber is often considered highly 'elastic' due to its large stretchability, matching the provided key, though in rigorous physics, steel has a higher elastic modulus.

Materials that undergo permanent deformation and do not regain their original shape are known as plastic materials.

Wood generally breaks or permanently deforms rather than elastically returning to its shape, as designated by the provided answer key.

Elasticity is the inherent property of a material that allows it to return to its original shape after the deforming force is removed.

While the force itself is a deforming force, the provided key selects option C (Both A and B).

Extension is inversely proportional to the square of the diameter (area). Halving the diameter reduces the area to 1/4th, thereby increasing the extension to four times its original value.