It is desirable that the standards of units be easily available, invariable, indestructible and easily reproducible. If we use foot of a person as a standard unit of length, which of theabove features are present and which are not?

Our monthly electricity bill contains a basic charge, which does not change with number of units used, and a charge that depends only on how many units we use. Let us say Electricity board charges Rs 110 as basic charge and charde Rs. 4 for each unit we use. If a person wants to keep his electricity bill below Rs. 250. then what should be his electricity usage

What meant by one candela? And Which base quantity is measured by this unit? (or) Define one candela (S.I standard for Luminous intensity)

A calorie is a unit of heat or energy and it equals 4.2 J where 1J = 1 kg m^(2)s^(-2) . Suppose we employ a system of units in which unit of mass is alpha kg. unit of length is beta m, unit of time is gamma . What will be magnitude of calorie in terms of this new system?