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Chemistry · Some Basic Concepts of Chemistry
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Chemistry · Some Basic Concepts of Chemistry
In the modern SI system, the unit of mass (kilogram) is defined by fixing the numerical value of which fundamental physical constant along with the definitions of metre and second?
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Who put forth the Law of Conservation of Mass in 1789 after performing careful experimental studies on combustion reactions?
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Dinitrogen and dihydrogen react with each other to produce ammonia according to the chemical equation: \( \text{N}_2(\text{g}) + 3\text{H}_2(\text{g}) \rightarrow 2\text{NH}_3(\text{g}) \). Calculate the mass of ammonia produced if \( 2.00 \times 10^3\text{ g} \) of dinitrogen reacts with \( 1.00 \times 10^3\text{ g} \) of dihydrogen.
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Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Constituents of a heterogeneous mixture can often be separated using simple physical methods such as filtration or hand-picking. Reason (R): In any mixture, the constituent particles always combine chemically in a fixed, definite mass ratio. In the light of the above statements, choose the correct answer from the options given below:
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A sample of matter possesses a definite volume but no definite shape, adapting to the shape of the container it occupies. At the microscopic level, the particles are:
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Consider the following statements regarding fundamental SI units: (A) The SI unit of thermodynamic temperature is Celsius. (B) The SI unit of luminous intensity is candela. (C) The SI unit of amount of substance is mole. (D) The SI unit of electric current is Coulomb. Which of the above statements are correct?
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Continuing from the previous problem, if the empirical formula mass of \( \text{CH}_2\text{Cl} \) is 49.48 g and the molar mass is 98.96 g, what is the molecular formula of the compound?
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If the speed of light is \( 3.0 \times 10^8\text{ m s}^{-1} \), calculate the distance covered by light in \( 2.00\text{ ns} \).
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Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).\n Assertion (A): One atomic mass unit (amu) is defined as a mass exactly equal to one-twelfth the mass of one carbon-12 atom.\n Reason (R): Carbon-12 isotope is selected as the standard for defining atomic masses since 1961. \nIn the light of the above statements, choose the correct answer from the options given below:
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A sample of hard water contains \( 120\text{ mg} \) of \( \text{MgSO}_4 \) (molar mass \( 120\text{ g mol}^{-1} \)) per litre. What is the concentration of magnesium ions expressed in parts per million (ppm) by mass, assuming the density of water is \( 1.0\text{ g mL}^{-1} \)?
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Match List-I with List-II: List-I (Base Physical Quantity) List-II (Symbol of Quantity & SI Unit Symbol) A Amount of substance I \( I\text{ and }\text{A} \) B Electric current II \( T\text{ and }\text{K} \) C Luminous intensity III \( n\text{ and }\text{mol} \) D Thermodynamic temperature IV \( I_v\text{ and }\text{cd} \) Choose the correct answer from the options given below:
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Given below are two statements: Statement I: One atomic mass unit (amu or u) is defined as a mass exactly equal to one-twelfth the mass of one carbon-12 atom. Statement II: Average atomic mass is calculated by taking the arithmetic mean of atomic masses of all naturally occurring isotopes. In the light of the above statements, choose the most appropriate answer from the options given below:
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When \( 22.4\text{ L} \) of \( \text{CO}_2 \) gas at STP is passed through an excess aqueous solution of \( \text{Ca(OH)}_2 \), the mass of precipitate formed is:
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A metal forms two oxides. In one oxide, \( 1.0\text{ g} \) of the metal combines with \( 0.266\text{ g} \) of oxygen. In the other oxide, \( 1.0\text{ g} \) of the metal combines with \( 0.400\text{ g} \) of oxygen. This observation illustrates the:
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Given below are two statements: Statement I: The International System of Units (SI) recognises exactly seven base physical quantities. Statement II: The SI unit of luminous intensity is the ampere, represented by the symbol A. In the light of the above statements, choose the most appropriate answer from the options given below:
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Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The atomic mass of an element is expressed relative to \( ^{12}\text{C} \) isotope of carbon. Reason (R): \( ^{12}\text{C} \) isotope was assigned a mass of exactly \( 12\text{ atomic mass units (u)} \) by IUPAC. In the light of the above statements, choose the correct answer from the options given below:
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Under identical conditions of temperature and pressure, \( 60\text{ mL} \) of a gaseous hydrocarbon requires \( 300\text{ mL} \) of dioxygen for complete combustion and produces \( 180\text{ mL} \) of carbon dioxide. The molecular formula of the hydrocarbon is:
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What mass of \( \text{CaCO}_3 \) is required to react completely with \( 25\text{ mL} \) of \( 0.75\text{ M} \text{ HCl} \)? (Atomic masses: \( \text{Ca} = 40, \text{C} = 12, \text{O} = 16 \))
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At what temperature do the numerical values on the Fahrenheit scale and the Celsius scale become identical?
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Calculate the molarity of a solution of ethanol in water, in which the mole fraction of ethanol is \( 0.040 \) (assume the density of water to be \( 1\text{ g mL}^{-1} \)).
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An organic compound contains \( 40\% \) carbon, \( 6.67\% \) hydrogen, and the remaining is oxygen. If its molecular mass is \( 180\text{ g mol}^{-1} \), its molecular formula is:
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Which one of the following will have the largest number of atoms? (Atomic masses: \( \text{Au} = 197, \text{Na} = 23, \text{Li} = 7, \text{Cl} = 35.5 \))
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