Carbon dioxide can be obtained in a number of ways. For example,
a. By burning of coke in air.
b. By the thermal decomposition of lime stone.
c. By the action of dilute hydrochloric acid on washing soda.
Based on the information, answer the following questions:
i. Is the composition of the constituent elements is different in compounds obtained
from different sources?
ii. In what ratio are the two elements combined?
iii. In what ratio by mass are the two elements combined?
iv. Is the ratio a simple whole number?
v. Which law of chemical combination is supported?
Answers
Answer:
Which of the following is not a physical change?
Boiling point of water to give water vapour
Melting point of ice to give water
Dissolution of salt in water
Combustion of Liquified Petroleum Gas(LPG)
Answer : d
2. The following reaction is an example of a 4NH3 (g) + 502 (g) à 4NO (g) + 6 H2 O (g)
Displacement Reaction
Combination Reaction
Redox Reaction
Neutralisation Reaction
1 and 4
2 and 3
1 and 3
3 and 4
Answer : c
Explanation :
A redox reaction is combination of oxidation (removal of hydrogen) and reduction (addition of hydrogen). Displacement reaction involves displacement of some part of a compound with other atom like H atoms of NH3 are displaced by oxygen.
3. Which of the following statements about the given reaction are correct?
3 Fe(s) + 4 H2O (g) à Fe3O (s) + 4 H2 (g)
Iron metal is getting oxidised.
Water is getting reduced.
Water is acting as reducing agent.
Water is acting as oxidizing agent.
1, 2 and 3
3 and 4
1, 2 and 4
2 and 4
Answer : c
Explanation: Addition of oxygen to Fe is an oxidation process whereas lose of oxygen from H2O to H2 is a reduction step. Since water is source of oxygen therefore it acts as oxidizing agent.
4. Which of the following are exothermic processes?
Reaction of water with quick lime
Dilution of an acid
Evaporation of water
Sublimation of camphor (crystals)
1 and 2
2 and 3
1 and 4
3 and 4