What is a sign that a chemical change has happened? O A. A substance dissolves.
O B. Sound and heat are produced.
OC. A substance changes temperature.
O D. A change of state happens.

What is the composition, in atom percent, of an alloy that consists of 4.5 wt% pb and 95.5 wt% sn? the atomic weights for pb and sn are 207.19 g/mol and 118.71 g/mol, respectively.(a) 2.6 at% pb and 97.4 at% sn(b) 7.6 at% pb and 92.4 at% sn(c)97.4 at% pb and 2.6 at% sn(d) 92.4 at% pb and 7.6 at% sn

What are the percent by mass of copper in penny lab

The formation of a solid, also known as a is an indication of a chemical change. precipitate particulate particle powder