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Read the text about the metric system and answer which sentences below it are true and which are false.

The Metric System. The metric system is the international decimal system of weights and measures based on the metre and kilogram.

The metre, the unit of length, is defined in terms of the bar of platinum-indium known as the international prototype metre at the International Bureau.

This is a line standard of length made with a cross section known as the Tresca section, selected because of its great rigidity for a giv­en weight, and having microscopic lines engraved on the plane of its neutral axis.

The composition of the alloy is 90% platinum, 10% iridium. The distance between the central and one of the group of lines at each end when the bar, being subjected to normal atmospheric pres­sure, is supported on two rollers at least 1 centimetre in diameter placed symmet­rically 572 mm. apart and the bar is at temperature of 0 °C. is defined as one metre.

It was shown by Albert Abraham Michelson that a standard of lengths could be replaced by reference to the measurement of wave length of light. In 1927 the Seventh General (International) Con­ference on Weights and Measures adopt­ed provisionally a supplementary defi­nition of the metre in terms of the wave length of light. According to this def­inition the relation for red cadmium light waves under specified conditions of tem­perature, pressure and humidity is 1 metre = 1,553,164.13 wave lengths. The kilogram is the mass of a definite platinum-iridium standard, the international prototype kilogram, kept at the International Bu­reau of Weights and Measures. The composition of this cylinder, which has a height approximately equal to its diameter, is the same as that of the prototype metre, namely, 90% platinum and 10% iridium.

The litre is defined as the volume of a kilogram of pure water at the temperature of its maximum density and under standard pressure [2, С. 42 - 43].

False or true?

1. The weights and measures of the metric system are based on the metre and kilometer.

2. The platinum-indium alloy consists of 90% platinum and 10% iridium.

3. In the 30s of the 20^th century the explanation of the metre with the help of the wave length of light was adopt­ed.

4. One litre may be defined as the volume of a kilogram of any liquid at the temperature of its maximum density and under standard pressure.

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