Chemical equation and reaction
Magnesium ribbon is rubbed before burning because it has a coating of
(a) basic magnesium carbonate
(b) basic magnesium oxide
(c) basic magnesium sulphide
(d) basic magnesium chloride
Color of copper oxide?
(a) blue
(b) black
(c) green
(d) brown
Which of the statements about the reaction below are incorrect? 2PbO(s) + C(s) → 2Pb(s) + CO2(g). (a) Lead is getting reduced. (b) Carbon dioxide is getting oxidised. (c) Carbon is getting oxidised. (d) Lead oxide is getting reduced.
(i) (a) and (b)
(ii) (a) and (c)
(iii) (a), (b) and (c)
(iv) all
Fe₂O₃ + 2Al → Al₂O₃ + 2Fe The above reaction is an example of a
(a) combination reaction.
(b) double displacement reaction.
(c) decomposition reaction.
(d) displacement reaction.
Which of the following are exothermic processes? (i) Reaction of water with quick lime (ii) Dilution of an acid (iii) Evaporation of water (iv) Sublimation of camphor (crystals)
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) (ii) and (iv)
The process of reduction involves
(a) addition of oxygen
(b) addition of hydrogen
(c) removal of oxygen
(d) removal of hydrogen
When Ag is exposed to air it gets a black coating of
(a) AgNO₃
(b) Ag₂S
(c) Ag₂O
(d) Ag₂CO₃
Which of the following is an endothermic process?
(a) Dilution of sulphuric acid
(b) Sublimation of dry ice
(c) Condensation of water vapours
(d) Respiration in human beings
What type of chemical reactions take place when electricity is passed through water?
(a) Displacement
(b) Combination
(c) Decomposition
(d) Double displacement
Select the oxidising agent for the following reaction: H₂S + I₂ --> 2HI + S
(a) I₂
(b) H₂S
(C) HI
(d) S
Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is:
(a) 1 : 1
(b) 2:1
(c) 4:1
(d) 1:2
Pb + CuCl₂ → PbCl₂ + Cu The above reaction is an example of:
(a) combination
(b) double displacement
(c) decomposition
(d) displacement
Which of the following gases can be used for storage
(a) Carbon dioxide or Oxygen
(b) Nitrogen or Oxygen
(c) Carbon dioxide or Helium
(d) Helium or Nitrogen
The chemical formula of lead sulphate is
(a) Pb₂SO₄
(b) Pb(SO₄)₂
(c) PbSO₄
(d) Pb₂(SO₄)₃
Chemically rust is
(a) hydrated ferrous oxide
(b) only ferric oxide
(c) hydrated ferric oxide
(d) none of these
Both CO₂ and H₂ gases are
(a) heavier than air
(b) colourless
(c) acidic in nature
(d) soluble in water
Fatty foods become rancid due to the process of
(a) oxidation
(b) corrosion
(c) reduction
(d) hydrogenation
Rancidity can be prevented by
(a) adding antioxidants
(b) storing food away from light
(c) keeping food in refrigerator
(d) all of these
The reaction of H₂ gas with oxygen gas to form water is an example of
(a) combination reaction
(b) redox reaction
(c) exothermic reaction
(d) all of these reactions
On immersing an iron nail in CuSO₄ solution for few minutes, you will observe
(a) no reaction takes place
(b) the colour of solution fades away
(c) the surface of iron nails acquire a black coating
(d) the colour of solution changes to green