(b) When capital is used again and again, it depreciates. For example, if any machine is used for a considerable period of time, then it may not be suitable for future use due to depreciation and have to be replaced after some time. Therefore, the producer has to keep some fund every year for the replacement of machinery and this is known as depreciation fund. 

(c) Double coincidence of wants means both the buyer and seller should be ready to exchange the goods. It is the major limitation of the barter system. By separating the act of sale and purchase, money has overcome the problem of double coincidence of wants. 

(d) COPRA stands for Consumer Protection Act. The central government legislated it in the year 1986 which not only recognizes consumer rights but has also established a redressal system unique in the world. The objective of the Act is to provide for the better protection of the interests of consumers and for that purpose to make provisions for the establishment of consumer councils in each state by the respective state government. 

(e) Indirect taxes sometimes help in social reforms. The statement is true. Heavy indirect taxes are imposed on articles which are undesirable and injurious to health like wine, cigarettes, opium etc. by the government and serve a great social purpose. It will restrict their consumption by the public. Curtailment of consumption of harmful goods increases social welfare.