Q. Naphthalene burns with a yellow sooty flame. This is because -
1) carbon to hydrogen ratio is low
2) there is incomplete combustion
3) there is an excess supply of air
4) of the presence of impurities of nitrogen and sulfur
Q. Which of the following statements are true for the reaction of Fe2O3 with aluminium?
1. It is known as the 'thermite reaction'.
2. The heat evolved is used for welding purposes.
3. Aluminium metal acts as an oxidizing agent.
4. Molten Fe and Al are formed at the end of the reaction.
Select the correct answer using the code given below -
1) 1 and 2
2) 1 and 3
3) 2 and 4
4) 1 and 4
Q. Which of the following elements is not suitable for the fabrication of a light-emitting diode structure?
1) Gallium phosphide
2) Indium gallium nitride
3) Germanium
4) Gallium arsenide
Q. The smallest possible unit of a chemical compound is -
1) Atom
2) Electron
3) Proton
4) Molecule
Q. A solution with pH =2 is more acidic than a solution of pH = 6 by a factor of -
1) 4
2) 12
3) 400
4) 10000
Q. What is washing soda?
1) Sodium chloride
2) Hydrated sodium carbonate
3) Sodium bicarbonate
4) Calcium carbonate
Q. The Chemical Formula of sulphuric acid is -
1) H2SO4
2) HSO4
3) HCL
4) H2SO3
Q. Which of the following will replace hydrogen from acids to form salts?
1) S
2) Na
3) Ag
4) P
Q. Which one of the following minerals does not contain Oxygen?
1) Haematite
2) Bauxite
3) Cryolite
4) Calcite
Q. The chemical name of common salt is -
1) Sodium Chloride
2) Sodium Bicarbonate
3) Sodium
4) Sodium Oxide