100 points answer hurry
how is a pure substance different from a
a. pure substances are made of mixtures
b. a pure substance is heterogeneous
c. a mixture is made of one substance
d. mixtures can be separated by physical means

The correct answer would be:

D. Mixtures can be separated by physical means. 

A pure substance is different from a mixture because D. mixtures can be separated by physical means. You can eliminate all of the other answers to find this out. A is incorrect because a pure substance is just that, a pure substance, while a mixture is multiple substances. B is incorrect because a pure substance is one substance, while heterogeneous is a type of mixture, which has multiple substances. And C is incorrect because a mixture is a blend of 2 or more substances.

the catch is that the top numbers are atomic masses the bottom numbers are the numbers of protons and electrons in an uncharged atom. they are the number of that atoms as you would find them on the periodic table. further, the numbers on the left are used to determine the missing numbers on the right

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer

Thermohaline circulation and gyres