Cusec, short for cubic feet per second, measures the flow rate of water, corresponding to option [C]. It quantifies the volume of water passing a particular point in a watercourse per unit of time. Cusec is commonly used to assess river flow, irrigation water supply, and water discharge from dams or reservoirs. Understanding flow rates is crucial in hydrology, agriculture, civil engineering, and environmental monitoring. For example, in irrigation, cusec helps determine the volume of water needed to irrigate crops efficiently. In hydroelectric power generation, cusec aids in evaluating the potential energy production of a river. By measuring water flow, cusec provides valuable information for water resource management, flood control, and ecosystem preservation efforts. Accurate measurement and interpretation of cusec data enable informed decision-making and sustainable utilization of water resources in various sectors, contributing to efficient water management and environmental stewardship.

Pascal is the unit of pressure, corresponding to option [B]. Named after the French mathematician and physicist Blaise Pascal, it is defined as one newton per square meter (N/m²). Pressure measures the force applied perpendicular to the surface of an object per unit area. Pascal is commonly used in various fields, including physics, engineering, meteorology, and fluid dynamics, to quantify pressure in different contexts. In meteorology, for example, atmospheric pressure is often measured in pascals to understand weather patterns and predict changes in atmospheric conditions. In engineering, pascals are used to determine stress and strain in materials under different loads. Understanding pressure is essential for numerous applications, from designing structures that withstand external forces to maintaining optimal conditions in industrial processes. Pascal’s unit provides a standardized and universal measure for quantifying pressure across diverse scientific and engineering disciplines.

Conservation of energy, denoted by option [D], states that energy can neither be created nor destroyed; it can only change forms or be transferred from one object to another. This principle, based on the first law of thermodynamics, asserts that the total energy of an isolated system remains constant over time, regardless of any internal changes. While energy transformations occur within the system, the total energy content remains constant. This fundamental concept underpins many scientific principles and practical applications, from understanding the behavior of physical systems to engineering design and environmental studies. Conservation of energy provides a powerful framework for analyzing and predicting the behavior of complex systems, ensuring that energy is accounted for and properly managed in various contexts, from mechanical systems to chemical reactions to celestial phenomena.

Capillarity is not the only reason for the movement of water from the roots of the plant towards its foliage, as described by option [D]. While capillarity aids in water uptake by plants, other processes such as transpiration and root pressure also contribute significantly to the movement of water within the plant. Transpiration, the loss of water vapor from leaves, creates a negative pressure gradient that pulls water up from the roots. Root pressure, generated by osmotic processes in the roots, also helps push water upwards. Together, these mechanisms facilitate the movement of water through the plant’s vascular system, ensuring hydration and nutrient transport to all parts of the plant. Therefore, while capillarity plays a role in water absorption and movement, it is not the sole reason for water transport from the roots to the foliage in plants.

In a state of weightlessness, the shape of a candle flame will become spherical, denoted by option [C]. Without the force of gravity, there’s no upward direction, so convection currents don’t form. Consequently, the flame doesn’t elongate upwards, instead, it expands in all directions equally, forming a spherical shape. This phenomenon is observed in microgravity environments like space, where objects experience weightlessness and gravitational effects are minimized. Therefore, in such conditions, the candle flame deviates from its typical teardrop shape seen on Earth and adopts a spherical form. This change in shape is due to the absence of gravitational force pulling the flame upward, leading to a more symmetric distribution of heat and gases around the flame’s core.