Answer:
The International System of Units (SI) is originated in France by frenches and originally was called a metric system of measurements. It provides definitions of various units of measurement such as weight, distance, electric current, temperature, and others which is widely accepted in the different fields of science and technology.
It is the system that is extended and derived from the french metric system of measurement is accepted in 1960 by convention 44 nation of the world to use particular unit of measurement worldwide to avoid confusion.
<u>Answer:</u> The mass percent of lead in lead (IV) carbonate is 63.32 %
<u>Explanation:</u>
The given chemical formula of lead (IV) carbonate is 
To calculate the mass percentage of lead in lead (IV) carbonate, we use the equation:
Mass of lead = (1 × 207.2) = 207.2 g
Mass of lead (IV) carbonate = [(1 × 207.2) + (2 × 12) + (6 × 16)] = 327.2 g
Putting values in above equation, we get:
Hence, the mass percent of lead in lead (IV) carbonate is 63.32 %
The last row going across
Within a physical change, an element can change forms, such as going from solid to a liquid through melting. Color change can also occur during a physical change. Physical changes are very different from chemical changes. In a chemical change the element itself changes into something else within a reaction, such as combustion (burning).
Hope this helped
