The question asks about the immediate effect when water is added to cement. This involves understanding the fundamental chemical process known as hydration of cement.
C) Heat is generated. This is correct because the hydration of cement is an exothermic chemical reaction, releasing heat.
To determine what "Pascal-second" is the unit of, we need to recall the definitions and units of the physical quantities listed in the options.
Correct Option: C) Dynamic viscosity
The question asks to identify which instrument among the given options is NOT used for measuring perpendicular offsets in surveying. Perpendicular offsets are measurements taken at right angles to a main survey line to locate details. We need to evaluate each option based on its primary function in surveying.
Correct Option: A) A line ranger is used for ranging a straight line, i.e., establishing intermediate points on a straight line between two terminal points. It is not used for measuring or setting out perpendicular offsets.
This question asks about the phase system of a fully saturated soil. Understanding the components that make up soil (solids, water, and air) under different saturation conditions is key to answering this.
Soil Composition: Soil is generally considered a three-phase system consisting of solid particles, water, and air. These three phases occupy the total volume of the soil.
Saturated Soil Definition: A soil is said to be fully saturated when all the void spaces (pores) between the solid particles are completely filled with water. In this state, there is no air present in the voids.
Identifying the Phases: Since all the voids are filled with water, the only components present in a fully saturated soil are the solid soil particles and water. Therefore, it becomes a two-phase system.
Correct Option: C) Two phase system with soil and water
The question asks to identify which of the given trees yields hardwood. This requires knowledge of common tree types and their wood properties, specifically distinguishing between hardwoods and softwoods.
Correct Option: C) Shisham is a deciduous tree that produces hardwood, known for its strength and durability. It is widely used in furniture making and construction.
The question asks about the design philosophy adopted by the Indian Standard code IS 800:2007 for general construction in steel. Understanding the evolution of design methods in structural engineering is key to answering this.
D) Limit state method — IS 800:2007 is the Indian Standard code for general construction in steel, and it is explicitly based on the Limit State Method. This method accounts for both the ultimate strength of the structure and its serviceability requirements (like deflection, vibration, etc.) under various load combinations, using partial safety factors for loads and material strengths.
The question asks to identify the type of instrument an ohmmeter is. We need to recall the basic principles of operation for different types of electrical measuring instruments and how an ohmmeter measures resistance.
B) moving coil instrument. An ohmmeter fundamentally uses a moving coil galvanometer to measure the current that flows through the unknown resistance when a known voltage is applied. The scale is then calibrated in ohms.
The question asks for the appropriate instrument to measure a very high resistance. We need to evaluate the purpose and typical resistance range of each given option.
C) Megger — A Megger is specifically designed for measuring very high resistances, particularly insulation resistance, by applying a high DC voltage and measuring the resulting small current.
The question asks about the power source for a megger, which is an instrument used for measuring high insulation resistances. Understanding the operating principle of a megger and the type of voltage it requires is key to identifying its power source.
Correct Option: B) permanent magnet D.C. generator — A megger requires a high DC voltage for its operation. A permanent magnet DC generator is typically incorporated into the megger to supply this voltage, especially in older or hand-cranked models, making it self-sufficient for field use.
The question asks about the mechanism that provides controlling torque in a megger. A megger is an instrument used for measuring high insulation resistances. Understanding its working principle, particularly how the pointer is controlled, is key to answering this question.
Correct Option: C) In a megger, the controlling torque is provided by the interaction of the magnetic fields of the coils, specifically the pressure coil which acts as the control coil. This is a fundamental design characteristic of a megger, allowing it to measure resistance over a wide range without external control springs.