Railway RRB / NTPC - MCQ Practice Questions

Methane (CH₄) is the main component of natural gas, comprising about 70-90% of its composition. It is the simplest hydrocarbon and is widely used as a fuel.

The kidneys are bean-shaped organs that filter waste products and excess water from the blood to produce urine. A human typically has two kidneys.

Newton's third law states that for every action, there is an equal and opposite reaction. This means forces always act in pairs - if object A exerts a force on object B, then B exerts an equal force on A in the opposite direction.

Insulin, produced by the pancreas, regulates blood glucose levels by promoting glucose uptake by cells.

Gravitational potential energy = mgh = 5 × 10 × 2 = 100 J

The pH scale ranges from 0 to 14, where 7 is neutral, below 7 is acidic, and above 7 is basic/alkaline.

Melting of ice is an endothermic process as it requires heat energy input to convert solid ice into liquid water. Other options are exothermic reactions that release heat.

The relationship between focal length (f) and radius of curvature (R) is: R = 2f. Therefore, R = 2 × 20 = 40 cm.