Unit-1 Nature of Science in Chemistry
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Unit-1 Nature of Science in Chemistry
Answer: Gold is an element, while salt, sugar and water are compounds.
Answer: Chlorophyll contains a magnesium atom at the centre of its structure.
Answer: By the law of conservation of mass, 2 g + 16 g = 18 g of water is formed.
Answer: Water is a compound of hydrogen and oxygen combined in a fixed ratio.
Answer: Oxygen is the most abundant element in the Earth's crust, present in oxides and silicates.
Answer: Fertilizers supply nutrients such as nitrogen, phosphorus and potassium that are needed for plant growth.
Answer: Diamond and graphite are different forms (allotropes) of the same element carbon.
Answer: Controlled variables are the factors kept constant so that only the independent variable affects the result.
Answer: NPK fertilizers supply nitrogen, phosphorus and potassium, the main nutrients for plant growth.
Answer: Diamond is the hardest natural substance because of its rigid three-dimensional structure.
Answer: Medicines are products of the pharmaceutical (drug) industry, which applies chemistry to make medicines.
Answer: In graphite, carbon layers are held by weak forces and slide over each other, making it slippery.
Answer: The temperature is the measured factor that changes in response to the heating, so it is the dependent variable.
Answer: Jabir bin Hayyan is considered the father of chemistry for his experimental methods.
Answer: Al-Razi grouped substances according to their mineral, vegetable or animal origin.
Answer: Antoine Lavoisier is regarded as the founder of modern chemistry for his careful quantitative experiments.
Answer: Al-Biruni developed methods to measure the density of substances, a key quantitative technique.
Answer: When mercury is heated, it combines with the oxygen part of air, showing that burning is combination with oxygen.
Answer: The scientific method begins with careful observation of a phenomenon.
Answer: Aqua regia is a mixture of concentrated hydrochloric and nitric acids, which can dissolve gold.