Answer:
open system
Coffee held in a cup is an open system because it can exchange matter water vapors and energy heat with the surroundings.
Answer : The correct option is, (2) Cr (Chromium)
Explanation :
The reactivity series of metal are arranged of the reactivity from the highest to the lowest. Reactivity series is used to determine the products of the single displacement reactions. In the single displacement reaction, the most reactive metal displaces the least reactive metal.
From the given reactivity series we conclude that there are two metal (Mg and Cr) are more reactive metal than the Ni and there are two metal (Pb and Cr) are less reactive metal than the Zn. So, the Cr (Chromium) is the metal which is more active than Ni and less active than Zn.
Hence, the correct option is, (2) Cr
The property of potential energy that distinguishes it from kinetic energy are Shape and position
Counting atoms in a compound can be done by taking one element at a time and multiplying the subscript of the element and the number of molecules of the compounds. For example, H2O, there are two atoms of H adn 1 atom of oxygen.