CGPSC MAINS 2020 Paper-4

Points to Remember: Dry corrosion is a chemical process. It occurs in the absence of an electrolyte. It’s primarily driven by atmospheric gases. Prevention involves material selection and protective coatings. Introduction: Corrosion is the deterioration of a material, usually a metal, due to a reaction with its environment. While wet corrosion (electrochemical corrosion) is widely … Read more

Points to Remember: The Information Village Project aims to bridge the digital divide. It focuses on providing access to information and communication technologies (ICTs). The project’s success depends on community participation and sustainability. Specific goals may vary depending on the implementation context. Introduction: The Information Village Project (IVP) is a community-based initiative designed to improve … Read more

Points to Remember: Optimal phosphorus (P) uptake by plants. Soil conditions influencing P availability. Crop-specific requirements. Environmental considerations (e.g., runoff). Economic factors (fertilizer costs). Introduction: Phosphorous (P) is a crucial macronutrient for plant growth, essential for root development, flowering, fruiting, and overall yield. Phosphatic fertilizers, containing various forms of phosphorus, are applied to supplement soil … Read more

Points to Remember: Potassic fertilizers are fertilizers that provide potassium (K) to plants. Potassium is an essential macronutrient for plant growth and health. Different potassic fertilizers have varying potassium content and other nutrient compositions. Introduction: Potassium is one of the three primary macronutrients (along with nitrogen and phosphorus) essential for optimal plant growth. Plants require … Read more

Points to Remember: The question asks for a list of renewable energy sources. The approach is purely factual. Introduction: Renewable energy sources are naturally replenishing energy sources that are virtually inexhaustible on a human timescale. Unlike fossil fuels (coal, oil, and natural gas), which are finite and contribute significantly to climate change, renewable energy offers … Read more

Points to Remember: The question involves code substitution. We need to replace the letters with their corresponding mathematical operations. The order of operations (PEMDAS/BODMAS) must be followed. Introduction: This question tests the ability to decipher a code and apply basic arithmetic operations. It involves substituting letters with mathematical symbols (+, -, ×, ÷) and then … Read more

Points to Remember: Probability is the likelihood of an event occurring. The sample space for throwing two dice is 36 possible outcomes. We need to identify the favorable outcomes where both dice show the same digit. Introduction: This question requires a factual and analytical approach to determine the probability of a specific event in a … Read more

Points to Remember: The question involves basic arithmetic operations with rational numbers. The core concept is finding an unknown number given its product with a known rational number. The solution requires understanding of fractions and their multiplication. Introduction: Rational numbers are numbers that can be expressed as the quotient or fraction p/q of two integers, … Read more

Points to Remember: Rational numbers are numbers that can be expressed as a fraction p/q, where p and q are integers, and q is not zero. To find rational numbers between two given rational numbers, we can find their average or use equivalent fractions with a common denominator. Introduction: This question requires a factual and … Read more

Points to Remember: This is a mathematical problem involving ratios and proportions. We need to find the unit cost of fans and ovens to solve the problem. The solution will involve setting up and solving a system of equations (or using ratios directly). Introduction: This question is a classic example of a problem involving proportional … Read more