Chemistry miscellaneous

Chemistry miscellaneous

Easy Questions
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Chemistry

Nature and Composition of Substances
Atomic Structure
Radioactivity
Periodic classification of element
Chemistry in Every Day Life
Biomolecules
Hydrocarbons and Its Derivatives
Non Metals and Their Compounds
Metals and Their Compounds
Surface Chemistry
Electrolytes & Electrochemistry
Solutions
Thermodynamics and Energetics
Catalysis
Properties of Gases
Acids, Bases and Salt
Oxidation and Reduction
Chemical Bonding
Chemistry miscellaneous
  1. Muddy water is treated with alum in purification process, itis termed as :








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    Natural and wastewater contain small particulates that are suspended in water forming a colloid. These particles carry the same charges, and repulsion prevents them from combining into larger particulates to settle. Historically, dirty water is cleaned by treating with alum, Al2(SO4)3.12 H2O, and lime, Ca(OH)2. The phenomenon is known as coagulation: Al2(SO4 )3 .12 H2O Al(aq)3+ + 3SO4(aq)2- + 12H2O SO4(aq)2- + H2O HSO4(aq)- + OH- (causing pH change) Ca(OH)2 Ca(aq)2+ + 2 OH- (causing pH change) The slightly basic water causes Al(OH)3, Fe(OH)3 and Fe(OH)2 to precipitate, bringing the small particulates with them and the water becomes clear.

    Correct Option: D

    Natural and wastewater contain small particulates that are suspended in water forming a colloid. These particles carry the same charges, and repulsion prevents them from combining into larger particulates to settle. Historically, dirty water is cleaned by treating with alum, Al2(SO4)3.12 H2O, and lime, Ca(OH)2. The phenomenon is known as coagulation: Al2(SO4 )3 .12 H2O Al(aq)3+ + 3SO4(aq)2- + 12H2O SO4(aq)2- + H2O HSO4(aq)- + OH- (causing pH change) Ca(OH)2 Ca(aq)2+ + 2 OH- (causing pH change) The slightly basic water causes Al(OH)3, Fe(OH)3 and Fe(OH)2 to precipitate, bringing the small particulates with them and the water becomes clear.

  1. Concentration of a material which is lethal to 50% animal is called








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    LD50 (Lethal Dose 50) is the amount of a solid or liquid material that it takes to kill 50% of test animals (for example, mice or rats) in one dose. LD50 is one way to measure the short-term poisoning potential (acute toxicity) of a material. LC50 is the concentration of a material in air that will kill 50% of the test subjects when administered as a single exposure.

    Correct Option: A

    LD50 (Lethal Dose 50) is the amount of a solid or liquid material that it takes to kill 50% of test animals (for example, mice or rats) in one dose. LD50 is one way to measure the short-term poisoning potential (acute toxicity) of a material. LC50 is the concentration of a material in air that will kill 50% of the test subjects when administered as a single exposure.

  1. If the equilibrium constants for the systems H2 + I2 ⇄ 2HI and 2HI ⇄ H2 + I2 are K1 and K2 respectively, the relationship between K1 and K2 is :








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    As per the Law of Mass Action, if Kf is the equilibrium constant for the equation A + B C + D, then 1/Kf is the equilibrium constant for the reverse equation, C + D A + B. So, as per the question K1 is the equilibrium constant for H2 + I2 2HI, then 1/K1 is equilibrium constant for the reverse equation 2 HI H2 + I2

    Correct Option: D

    As per the Law of Mass Action, if Kf is the equilibrium constant for the equation A + B C + D, then 1/Kf is the equilibrium constant for the reverse equation, C + D A + B. So, as per the question K1 is the equilibrium constant for H2 + I2 2HI, then 1/K1 is equilibrium constant for the reverse equation 2 HI H2 + I2

  1. When a bond is formed between two atoms, the energy of the system will








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    The fundamental reason for the bonding of atoms is that they lose their stored potential energy by forming bonds. This is the only reason for chemical combination. So, when a bond is formed between two atoms, stored potential energy is always released to the surroundings. However, according to the Law of Conservation of Energy, a bond cannot form unless this bond energy is transferred from the interacting atoms to the rest of the system. So overall the energy of the system remains the same.

    Correct Option: C

    The fundamental reason for the bonding of atoms is that they lose their stored potential energy by forming bonds. This is the only reason for chemical combination. So, when a bond is formed between two atoms, stored potential energy is always released to the surroundings. However, according to the Law of Conservation of Energy, a bond cannot form unless this bond energy is transferred from the interacting atoms to the rest of the system. So overall the energy of the system remains the same.

  1. Sodium Carbonate is commonly known as








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    Sodium carbonate (Na2CO3) is also known as washing soda, soda ash and soda crystals. It is a salt of carbonic acid, a chemical that produces a wide range of salts collectively known as carbonates. It can be used to remove stubborn stains from laundry.

    Correct Option: B

    Sodium carbonate (Na2CO3) is also known as washing soda, soda ash and soda crystals. It is a salt of carbonic acid, a chemical that produces a wide range of salts collectively known as carbonates. It can be used to remove stubborn stains from laundry.