Chemistry Questions and Answers

  • 26. The nitrogen atom has 7 protons and 7 electrons,The nitride ion will have
   A.) 4 protons and 7 electrons
   B.) 7 protons and 10 electrons
   C.) 10 protons and 7 electrons
   D.) 4 protons and 10 electrons

Answer: Option 'B'

7 protons and 10 electrons

  • 27. Among the following the maximum covalent character is shown by the compound




    (4) AlCl3

   A.) Option 1
   B.) Option 2
   C.) Option 3
   D.) Option 4

Answer: Option 'D'

According to Fajans rule, cation with greater charge and smaller size favours covalency.

  • 28. In nuclear reactor,Chain reaction is controlled by introducing
   A.) platinum rod
   B.) cadmium rod
   C.) iron rod
   D.) graphite rod

Answer: Option 'B'

cadmium rod

  • 29. Which one among the following is the heaviest
   A.) 1 mole of sodium atoms
   B.) 1 mole of water molecules
   C.) 1 mole of ammonia molecules
   D.) 1 mole of hydrogen molecules

Answer: Option 'A'

1 mole of sodium atoms

  • 30. The difference between a nuclear reactor and atomic bomb is that ___________
   A.) no chain reaction takes place in nuclear reactor while in the atomic bomb there is a chain reaction
   B.) the chain reaction in nuclear reactor is controlled
   C.) the chain reaction in nuclear reactor is not controlled
   D.) no-chain reaction takes place in atomic bomb while it takes place in nuclear reactor

Answer: Option 'B'

the chain reaction in nuclear reactor is controlled

  • 31. The bleeding of a wound is stopped by the application of ferric chloride because_____
   A.) Ferric chloride seals the blood vessels
   B.) Blood starts flowing in the opposite direction
   C.) Blood reacts and a solid is formed which seals the blood vessels
   D.) Blood is coagulated and the blood vessels are sealed

Answer: Option 'D'

Blood is coagulated and the blood vessels are sealed

  • 32. Brass gets discoloured in air because of the presence of which of the following gases in air?
   A.) Nitrogen
   B.) Hydrogen sulphide
   C.) Oxygen
   D.) Carbon dioxide

Answer: Option 'B'

Hydrogen sulphide

  • 33. Temporary hardness is due to the presence of 
   A.) magnesium sulphate
   B.) calcium bicarbonate
   C.) Calcium carbonate
   D.) calcium sulphate

Answer: Option 'B'

Temporary hardness is due to the presence of soluble bicarbonates of calcium and magnesium in water. Permanent hardness is due to the presence of sulphates and chlorides of calcium and magnesium.



  • 34. The reduction potential of hydrogen half-cell will be negative if :
    (1) P(H2)= 2 atm and [H+] = 2.0 M
    (2) P(H2)= 1 atm and [H+] = 2.0 M
    (3) P(H2)= 1 atm and [H+] = 1.0 M
    (4) P(H2)= 2 atm and [H+] = 1.0 M
   A.) Option 1
   B.) Option 2
   C.) Option 3
   D.) Option 4

Answer: Option 'D'

Option 4

  • 35. The hard Shell of an egg was dissolved in HCL. The egg was then placed in a concentration solution of NaCl. What will happens ______
   A.) The egg will become harder
   B.) The egg will swell
   C.) The egg will shrink
   D.) There will be hardly any visible change

Answer: Option 'C'

The egg will shrink

  • 36. An element which is preserved under water is 
   A.) red phosphorus
   B.) white phosphorus
   C.) sodium
   D.) sulphur

Answer: Option 'B'

White phosphorus undergoes spontaneous combustion when exposed to air. In order to prevent this spontaneous ignition, it is preserved under water. 

  • 37. The entropy change involved in the isothermal reversible expansion of 2 moles of an ideal gas from a volume of 10 dm3 at 27°C is to a volume of 100 dm3
   A.) 42.3 J/ mole / K
   B.) 38.3 J/ mole / K
   C.) 35.8 J/ mole / K
   D.) 32.3 J/ mole / K

Answer: Option 'B'

38.3 J/ mole / K

  • 38. The law of constant proportions was enunciated by
   A.) Avogadro
   B.) Proust
   C.) Dalton
   D.) Berthelot

Answer: Option 'B'


  • 39. Heated saw dust catches fire when a drop of concentrated nitric acid is added to it. This is due to
   A.) reduction
   B.) dehydration
   C.) oxidation
   D.) dehydrogenation

Answer: Option 'C'


  • 40. Which of the following is a Decomposition Reaction?
   A.) 2HgO ----> 2Hg + O2
   B.) 6NaNO3 ----> 6NaNO2 + 3O2
   C.) ZnCO3 ----> ZnO + CO2
   D.) All the above

Answer: Option 'D'

All the given reactions are Decomposition reactions.

Decomposition reaction is a reaction in which only one reactant is splitted into two or more products.

  • 41. Which of the following are chemical changes?
    A) Cooking of Food
    B) Digestion of Food
    C) Freezing of water
    D) Water is heated up
   A.) A & B
   B.) A, B & C
   C.) C & D
   D.) All the above

Answer: Option 'A'

A) Cooking of Food  ------ Chemical Change

B) Digestion of Food ----- Chemical Change

C) Freezing of water ----- Physical Change

D) Water is heated up ---- Physical Change

because here the chemical composition of the substance changes in A & B only.

Since we know that, If the chemical composition is changing then it is a chemical change and if the chemical composition is remaining the same, then it is a physical change.

  • 42. Which of the following is not a pure substance?
   A.) Water
   B.) Oxygen
   C.) Carbon dioxide
   D.) Milk

Answer: Option 'D'


  • 43. What is the systematic name of NH4ClO3?
   A.) Ammonium Chloride
   B.) Ammonium Chlorate
   C.) Ammonium Chlorane
   D.) Ammonium Chlorine

Answer: Option 'B'

In common we all call the systematic name of NH4ClO3NH4ClO3 as Ammonium Chlorate. But originally the systematic name is azanium trioxidochlorate.

  • 44. Which statement best describes electrons?
   A.) Electrons orbit around the nucleus
   B.) Electrons are composed of protons and neutrons
   C.) Electrons reside in the nucleus
   D.) Electrons have a positive charge

Answer: Option 'A'

Electrons orbit around the nucleus

  • 45. What are the Monomers that make up Proteins?
   A.) Amino acids
   B.) Nucleotides
   C.) Disaccharides
   D.) Chaperones

Answer: Option 'A'

Proteins are long chains of Amino acids. That is in brief, Amino acids are the monomers of Proteins. Amino acids are compounds which contain both an amino group and a carboxylic group. Proteins are made up of 20 essential amino acids.

Monomer means a small molecule of an organic substance i.e, building block in general.

  • 46. Acid Precipitation is caused by a mix of
   A.) Hydrogen, Oxygen, and Saline
   B.) Water, Soil, and Air
   C.) Respiration, Carbonic Acids, and Seawater
   D.) Sulfur Dioxide, Carbon Dioxide, Nitrogen Oxides

Answer: Option 'D'

Acid Precipitation or Acid rain is caused by a mix of Sulfur Dioxide, Carbon Dioxide, Nitrogen Oxides.

A Chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as Acid Rains.

  • 47. Which of the following equations represents Photosynthesis?
   A.) 6CO2 + 6H2O -----> C6H12O6 + 6O2
   B.) C6H12O6 + 6O2 -----> CO2 + 6H2O
   C.) CO2 + H2O -----> C6H12O6 + 6O2
   D.) 6O2 + 6H2O -----> C6H12O6 + 6CO2

Answer: Option 'A'

6CO2 + 6H2O -----> C6H12O6 + 6O2

  • 48. Which of the following is an Organic Molecule?
   A.) Nitrogen gas
   B.) Ammonia
   C.) Fructose
   D.) Water

Answer: Option 'C'

Fructose is an Organic molecule among the given options.

 Organic Molecules :

An organic molecule is one which contains carbon, although not all compounds that contain carbon are organic molecules. Noticeable exceptions are carbon monoxide (CO), carbon dioxide (CO2), carbonates (e.g. calcium carbonate), carbides (e.g. calcium carbide) and cyanides (e.g. sodium cyanide). Pure carbon compounds such as diamond and graphite are also not organic compounds. Organic molecules can range in size from simple molecules to complex structures containing thousands of atoms.

Although carbon is present in all organic compounds, other elements such as hydrogen (H), oxygen(O), nitrogen (N), sulfur (S) and phosphorus (P) are also common in these molecules.

In simple, Molecules needed for life that have carbon are called Organic Molecules.

  • 49. Ozone is concentrated in the
   A.) Ionosphere
   B.) Stratosphere
   C.) Troposphere
   D.) Mesosphere

Answer: Option 'B'

Most of the ozone in the atmosphere is found in the layer of stratosphere, which begins about 10.16 kilometers (6.10 miles) above Earth's surface and extends up to about 50 kilometers (31 miles) altitude.

  • 50. Tetraethyl lead is used as
   A.) Mosquito repellent
   B.) Gasoline additive
   C.) Fire extinguisher
   D.) Pain killer

Answer: Option 'B'

Tetraethyl lead is a highly toxic compound used as a gasoline additive.

Tetraethyl lead abbreviated as TEL, is an organo lead compound with the formula (CH3CH2)4Pb. It is a petro-fuel additive which in turn caused increased vehicle performance. This is also used as an antiknock agent in gasoline and jet fuels. Tetraethyl lead is absorbed rapidly by the skin, the lungs, and the gastrointestinal tract. It is converted to triethyl lead, which might be responsible for its toxicity.